TL;DR

• The median PR is updated once between publishing and merging (2 submits total). Additionally, the median user updates their PR once between publishing and merging.

  • This median of two submits per merged PR holds true across org size

• Two factors that affect how frequently changes are pushed to a PR include:

  • Whether the PR has any reviews (which may be self-perpetuating): the more reviews, the more commits before merging

  • The size of the PR: PRs under 50 lines, on median, are merged after publishing without any interstitial commits. In contrast, PRs over 500 lines are updated 5x after publishing (6 total commits including the initial push to remote).

    

  • Even when controlled by number of reviews, larger PRs have commits prior to merging

• This has implications on time spent waiting for CI runs and CI costs, which we will follow up on in a later research post.