The question is not whether to automate, but which parts need intelligence
Document processing, request classification, and data extraction are tasks that can make a large language model (LLM) seem like an obvious choice. It can interpret varied text and produce a structured response, but that does not make it the right option for every step. In an operational workflow, a wrong decision can trigger payments, rejections, account changes, or compliance failures. So choose based on the cost of errors and the guarantees the process needs—not on how attractive the tool seems.
It helps to distinguish three families. Deterministic rules apply explicit conditions and return the same result for the same input. Specialized predictive models learn to assign categories or scores from data and are evaluated for a specific task. Generative AI uses instructions and context to produce content or interpret flexible inputs; its output can change when the prompt or model changes. A single workflow can combine all three, assigning each to the tasks it handles best.
Google’s technical documentation distinguishes broad-purpose foundation models from predictive models designed for specific tasks. It also recommends considering quality, latency, cost, and compliance when evaluating a model for a use case. It provides no universal thresholds and does not establish that one family is always faster or cheaper: you need to measure the actual configuration using the data, volume, and infrastructure you expect to run.
1. Traceability and auditability: make every result explainable
When a decision must be justified to an auditor or an affected person, keeping only the final answer is not enough. The system should retain the relevant input, the version of the rules or model, the data consulted, the result, the checks performed, and any human intervention. For a generative system, you may also need to record the prompt template, model identifier, retrieved documents, and original response, subject to privacy and retention controls.
Rules are often easier to inspect: an explicit condition can be linked to a specific reason, such as “if the invoice number is missing, send it for review.” But readable rules do not guarantee that a process is lawful or correct. You still need to check that the policy is current, applied consistently, and versioned in the logs. Predictive models require different controls, such as recording versions, evaluation data, metrics, and changes in performance. LLMs add another challenge: a plausible answer is not, by itself, a verifiable explanation of how a decision was made.
Do not infer a specific legal requirement from an engineering recommendation. The available sources do not establish the precise obligations that the European Union’s AI Act imposes on each operational system, or whether a particular process falls within a regulated category. Classification depends on the system’s purpose, context of use, and configuration; it requires a legal assessment applicable to the case. As a design practice, it is reasonable to prepare reproducible records, access controls, human review, and ways to correct results—but do not present these as a complete list of legal requirements.
A useful minimum record for an automated decision
- 01Retain the necessary input and its source, applying data minimization and access controls.
- 02Record the version of the rule and model and, where relevant, the prompt template and sources consulted.
- 03Save the system’s output, the checks performed, and the case disposition: approved, rejected, or sent for review.
- 04Make it possible to reconstruct the decision and correct the data or result when an error is found.
2. Latency: measure the whole workflow, not just inference
In a strict real-time system, a response that arrives after the deadline can count as a failure. Before comparing technologies, define the end-to-end latency budget and where the clock starts and stops: from request arrival until the system executes or confirms the action. An LLM call can include network waits, context preparation, document retrieval, generation, and validation. Measuring generation time alone hides important parts of the time cost.
Rules are often a good fit for short, predictable checks; a lightweight predictive model may classify an input within a bounded time budget. However, it is not safe to claim that every classifier is faster than every LLM: performance depends on hardware, model size, input length, service, load, and architecture. Google’s documentation recommends evaluating latency and throughput for the use case. It distinguishes needs such as interactive conversation from batch summarization, but provides no comparable figures across models.
To compare alternatives, test them under representative load and measure percentiles, not just averages. Record at least p50, p95, and p99; error rate; requests per second; queue time; and the latency of each stage. Repeat the tests under normal load and expected peaks, and specify whether external calls are included. If the application has a strict deadline, define a fallback path that can respond within it—for example, apply known rules, return a pending status, or route the request for review instead of waiting indefinitely for a generative response.
What to measure before deciding
Collect metrics using the same configuration and test cases so the comparison is meaningful.
| Measure | How to use it | Risk it reveals |
|---|---|---|
| p95 and p99 latency | Measure end to end under representative load | Queues and slow cases hidden by the average |
| Cost per completed case | Include inference, retries, retrieval, and human review | An option that is cheap per call may be expensive per valid result |
| Error and retry rates | Record technical failures, invalid outputs, and retries | Missed deadlines and additional costs |
| Decision quality | Evaluate accuracy, coverage, and errors by category | A fast but incorrect response does not meet the goal |
| Fallback availability | Simulate model outages or an expired time budget | Dependence on a service with no controlled exit |
3. Consistency: when variability helps and when it gets in the way
Business rules should produce the same consequence for the same case: an amount over the limit is blocked; a missing required field is sent for review; a suspended account does not proceed to the next step. If a change in wording alters the decision, the system becomes difficult to test and maintain. Explicit rules are appropriate for conditions that are known, change in a controlled way, and require predictable results.
A model’s variability is not always a defect. It can add value when inputs are free-form, documents come in varied formats, or descriptions are incomplete in ways rigid rules do not handle well. A predictive classifier may be suitable when the goal is to assign a label from known categories and there is a set of examples for evaluation. An LLM can help normalize or summarize an input before rules or downstream systems check the decisive information. Treat any model’s output as a proposal until it passes the checks appropriate to the risk.
Foundation models can be sensitive to changes in instructions and inputs, and they need to be evaluated in the context of the specific application, including its templates and connected components. So you cannot test once and assume behavior will remain identical after changing the model, instructions, data, or chain. Maintain a representative test set, record versions, and compare results before deploying changes. For critical processes, define confidence limits or review conditions without assuming that a score alone proves the response is correct.
A decision matrix for choosing the main component
Make the final decision by workflow stage, not necessarily for the workflow as a whole. For each step, describe the input, the decision it must produce, which errors are acceptable, and the deadline it must meet. Then choose the simplest component that satisfies those requirements based on representative tests. A model may be justified when cases change frequently or contain highly variable language; when a condition is explicit and stable, a rule is often easier to verify.
Hybrid workflows are often a sensible choice: rules for limits and validation; predictive models for bounded classification; generative AI for interpreting, extracting, or summarizing ambiguous inputs; and human review for exceptions or high-impact actions. Orchestration should record each step and allow changes to be tested as a unit. Google’s documentation emphasizes continuous evaluation, artifact management, and monitoring for generative applications, though it does not prescribe a single architecture.
This framework does not replace an assessment of safety, privacy, compliance, or impact. Nor does it determine in advance which system will be cheaper or faster: those results depend on volume, infrastructure, maintenance, and the proportion of cases requiring review. Record assumptions and uncertainties, and measure again when data, rules, models, or operational requirements change. To explore options, compare alternatives, and learn about related concepts, visit Inferama’s internal routes: [discover](route:discover.index), [compare](route:compare.index), and [learn](route:learn.index).
Decision matrix by workflow type
This table can guide an initial choice; validate it against the data and requirements of the specific process.
| Dominant need | Initial option | When to add another option | Essential control |
|---|---|---|---|
| Explicit, auditable condition | Deterministic rules | If the input is ambiguous, add extraction or an initial classification step | Policy versioning, edge-case tests, and logging |
| Classification among known categories | Specialized predictive model | If text is open-ended or context is missing, add interpretation | Per-class metrics, thresholds, and error review |
| Interpreting varied documents or text | LLM or LLM-assisted extraction | If the action has fixed limits, validate it with rules afterward | Record input, version, output, sources, and checks |
| Strict deadline and predictable output | Rules or a locally evaluated lightweight model | If the case goes beyond what is known, queue or route it for review | p95/p99 measurement, fallback path, and time limit |
| Costly or high-impact exception | Hybrid workflow with human review | Automate further only after assessing risk and errors | Traceability, authorization, and a correction mechanism |
A short selection and deployment process
- 01Break the workflow into decisions and actions, identifying where an error could cause harm or cost.
- 02Define measurable requirements for quality, latency, traceability, and cost per valid case.
- 03Compare rules, a specialized model, and an LLM using the same sample cases and representative load.
- 04Design validation, human review, and a fallback path for uncertain inputs or failures.
- 05Record versions and results; deploy gradually and monitor errors, latency, cost, and changes in the data.
Conclusion: automate with only as much flexibility as needed
Generative AI is not a universal replacement for rules or predictive models. Its advantage is handling varied inputs and producing interpretations or content; its limitations matter when a process requires reproducible results, a strict deadline, or an audited explanation. A more robust design assigns each decision to the component that can resolve it verifiably and prevents a plausible-sounding output from automatically triggering an irreversible action.
Start with the cost of errors, applicable obligations, and the time budget. Use rules for explicit policies, predictive models for bounded tasks with evaluation data, and LLMs for ambiguity that justifies their flexibility. In every case, measure the real workflow, record what is needed to reconstruct decisions, and keep a safe alternative. If a pilot’s evidence does not let you compare quality, cost, and latency, there is not yet enough basis to choose on intuition alone.
Open questions
- The sources provided contain no comparable benchmarks for inference latency or cost between LLMs and predictive models; both depend on the task, infrastructure, load, and configuration.
- The available documentation does not determine specific EU AI Act traceability requirements for a particular workflow; its purpose, context, and applicable classification need to be assessed.
- The invoice, routing, and reimbursement examples illustrate design patterns; they are not empirical study results or documented performance tests.
- The use case does not specify volume, error tolerances, infrastructure, or jurisdiction, so the matrix is an initial guide rather than a definitive architecture recommendation.
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