"How long does it take to update docs after a release?" has a satisfying-sounding answer and a true answer, and they are not the same. The satisfying answer is a single average. The true answer is a distribution with a fast middle, a long tail, and a chunk of changes that never get documented at all, which no average can represent.
We measured the gap between a merged customer-facing change and its matching docs update across a large sample of open-source SaaS repositories. Reporting the median, the mean, and the tail together is the only honest way to describe it, so that is what this page does.
Direct answer
Among customer-facing changes that do get documented, the update is usually fast: the median lag is about 0.5 days, effectively same-day. But the mean is roughly 3.5 days because a long tail drags it up, with the slowest tenth of changes taking around 11 days or more. And that is only among changes that get documented at all: 20.3% of customer-facing changes get no docs update, and 6.3% are still undocumented long after merge. So the honest answer is "near-instant when it happens, but it often does not happen." Full methodology is in the State of Documentation Debt report.
The median is fast; the mean is not the median
When a team does document a change, they tend to do it right away, often in the same PR or the same day. That is why the median lag is only about 0.5 days. If you stopped there, docs would look effortlessly current.
But the mean tells a different story. At roughly 3.5 days, it sits well above the median, which is the classic signature of a long right tail: a minority of changes take much longer, and a few take weeks. Quoting the average alone overstates the typical wait and hides the changes that quietly rot.
| Measure | Value (days) | What it tells you |
|---|---|---|
| Median | 0.5 | Typical documented change: essentially same-day |
| 75th percentile | 3 | Three in four documented changes land within this |
| 90th percentile | 11 | The slow tail begins here |
| Mean | 3.5 | Pulled up by the tail; higher than the median |
The number the average leaves out
Every figure above is computed only over changes that eventually got documented. That is a big asterisk, because it silently drops the changes that never did.
- 20.3% of customer-facing changes received no docs update at all, so they have no "time to update" because the update never came.
- 6.3% were still undocumented well past the 30-day window we treat as permanent debt.
- Counting those as infinite lag, the real "average time to update" is undefined, which is exactly why a single average is misleading.
What makes the slow tail slow
- The change shipped without anyone connecting it back to a specific article.
- The person who knows what changed is not the person who owns the docs.
- The update waits on a manual review cycle or a batched "docs day" that keeps slipping.
Each of these is a handoff gap, not a writing-speed problem. Remove the handoff and the tail collapses. For how that works in practice, see How DocsKoala works.
How to make the lag near-zero and complete
- Trigger the docs update from the merge itself, so the clock starts at zero.
- Draft from the diff so a reviewable update exists immediately, not after someone finds time.
- Keep a one-click human approval so the fast path does not sacrifice accuracy.
That is the loop DocsKoala automates: draft on merge, approve in one click, publish. To see what closing the lag on your own repository would cost, the pricing page covers the trial and paid tiers.
Frequently asked questions
What is the average time to update documentation after a release?
Among changes that get documented, the median lag is about 0.5 days (near same-day) and the mean is roughly 3.5 days, higher because of a long tail. But 20.3% of customer-facing changes are never documented, so a single average understates the real problem.
Why is the mean higher than the median for docs updates?
Because the distribution has a long right tail. Most documented changes are updated quickly, but a minority take much longer, and those slow cases pull the mean above the median. It is a sign that the typical case and the worst case are very different.
Does a fast median mean documentation is healthy?
Not on its own. A fast median only describes changes that got documented. The health of your docs depends more on the completion rate, and in our audit 20.3% of customer-facing changes got no update at all.
How do teams get both fast and complete documentation?
They trigger the update from the merge, draft it from the diff so it exists immediately, and keep a quick human approval. That collapses the slow tail and raises the completion rate at the same time.
Conclusion
- When docs get updated, the median lag is near same-day (about 0.5 days).
- The mean (~3.5 days) sits above the median because of a long tail.
- Those numbers exclude the 20.3% of changes that are never documented at all.
- So the real problem is completion, not writing speed.
- See the full report, or make the lag near-zero with the DocsKoala trial.