A free AI coding tier saves you roughly $19–$45 per seat per month in subscription fees. It costs you something harder to see: every hour your team spends reviewing, reworking, and governing AI-assisted output. If rework eats more than about 6–8% of assisted throughput, the free pilot is more expensive than the paid tool you declined to buy. Most teams never measure this, so the pilot drifts into permanent shadow infrastructure.
This article gives you an exit review: three numbers to collect during the pilot, a worked break-even table, and a promote / extend / stop decision with an owner and an expiry date. The scorecard is a conversation tool, not objective truth — the thresholds matter less than agreeing on them before the data arrives.
Why exit reviews fail
Pilot gating gets all the attention. Teams write intake checklists, blast-radius routing rules, and security reviews before day one — then day thirty arrives and the decision is made by whoever has the strongest anecdote. The failure mode is not recklessness; it is measurement asymmetry: costs are diffuse (review time, rework, on-call interruptions) while savings are concentrated and legible (zero invoice).
The fix is to instrument the pilot like a P&L, with costs and returns in the same unit: engineer-hours.
Where a free pilot fits
A zero-cost tier is the right vehicle for exactly this kind of measurement, because the experiment itself should not require budget approval. MonkeyCode, for example, offers free model access and a free server option, which means a platform lead can stand up a pilot environment and collect thirty days of real usage data without a procurement cycle.
Disclosure: This article was prepared as part of MonkeyCode's product outreach. Treat those availability claims as a starting point, not a commitment — free tiers change, so the review below explicitly prices the risk that the tier disappears or its terms shift. Do not assume quotas, model quality, or duration you have not verified yourself this month.
The three numbers
Collect these weekly, per developer, for the pilot group plus a matched control group doing similar work without the tool:
- Assisted throughput (T) — tasks or story points completed where the tool materially contributed. Be honest: if the developer would have finished anyway, it does not count.
- Rework rate (R) — share of assisted output that needed substantive correction within one sprint: reverted suggestions, bugs traced to generated code, review rounds beyond the team's norm.
- Governance overhead (G) — hours per week spent on prompt hygiene, output review beyond normal code review, dependency checking of suggested packages, and policy enforcement.
Variables, made explicit:
Net value per week (hours) = T × S − T × R × C − G
S = hours saved per assisted task (vs. control-group baseline)
C = hours to fully rework one bad assisted task
A worked example (illustrative numbers — replace with yours)
Pilot: 8 developers, 4 weeks. Control group: 5 developers on comparable tickets.
| Week | T (assisted tasks) | S (hrs saved/task) | R (rework) | C (hrs/rework) | G (hrs) | Net (hrs) |
|---|---|---|---|---|---|---|
| 1 | 22 | 1.5 | 18% | 3.0 | 9 | 22×1.5 − 22×0.18×3 − 9 = +12.1 |
| 2 | 31 | 1.4 | 12% | 3.0 | 7 | +21.3 |
| 3 | 35 | 1.4 | 9% | 3.5 | 6 | +31.9 |
| 4 | 38 | 1.3 | 8% | 3.5 | 6 | +32.8 |
Two things to notice. First, rework rate falling week over week is the real signal — it means the team is learning routing, not that the tool improved. Second, governance overhead is sticky; if G does not decline by week three, it never will without a policy change.
Break-even and sensitivity
The question that reverses decisions: at what rework rate does this pilot go negative?
Using week 4 values and holding T, S, C, G constant:
Net = 38 × 1.3 − 38 × R × 3.5 − 6 = 0
R* = (49.4 − 6) / 133 ≈ 32.7%
Headroom looks large — until you stress the other variables:
- If S drops to 0.8 hrs (tasks turn out to be easier than estimated), R* falls to ~17%. Now one bad week of rework kills the month.
- If the free tier's terms change and you migrate to a paid seat at $25/dev/month (~0.4 hr of loaded cost), net barely moves. This is why the tier disappearing is not, by itself, a stop condition.
- If C rises to 6 hrs (rework discovered in production instead of review), R* drops to ~23% and G must rise to compensate. Blast radius re-enters the P&L whether you gated for it or not.
Run the table under pessimistic S and pessimistic C. If the pilot only clears break-even under optimistic assumptions, that is your answer.
The exit decision table
Set these thresholds on day one, with a named owner (typically the platform lead) and a review date:
| Signal | Promote (make it standard) | Extend 30 days | Stop |
|---|---|---|---|
| Net hours/week, weeks 3–4 avg | > 1.5 hrs/dev | 0.5–1.5 | < 0.5 |
| Rework trend | Falling for 3 consecutive weeks | Flat | Rising |
| Governance overhead | ≤ 0.75 hr/dev/week and falling | Falling but above 0.75 | Flat or rising |
| Control-group gap | ≥ 20% throughput delta | 10–20% | < 10% |
Extend at most once. A second extension means the pilot design is broken, not the tool — usually the control group is mismatched or assisted-task counting is inflated.
Limitations and who should skip this
- Small teams (under ~6 developers): your control group is too small to mean anything. Use a before/after baseline on the same team instead, and double the pilot length.
- Regulated or high-blast-radius codebases: rework cost C is not 3.5 hours, it is an incident. Price it as one, and the free tier will rarely clear the gate — that is a correct outcome.
- Teams without ticket-level data: if you cannot measure S honestly, do not run the P&L on vibes. Fix instrumentation first; the pilot can wait a sprint.
- Anyone treating the review as a formality: if "promote" is pre-decided, you are writing procurement theater, and the control group will notice.
If you want a low-friction environment to run this measurement, a free tier with free model access and a self-hostable server — MonkeyCode is one current option — keeps the experiment's fixed cost near zero, which is exactly what an honest pilot needs. The tool is the easy part.
Which threshold in the decision table would actually reverse your team's answer — rework rate, governance overhead, or the control-group gap? If none of them would, the review is already decided and the thirty days are a ritual.
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