I work on a project with a 3 hour CI process that handles about 15 to 40 PRs a day. The problem you describe here is a real challenge. Our PRs don't use a merge

I work on a project with a 3 hour CI process that handles about 15 to 40 PRs a day. The problem you describe here is a real challenge. Our PRs don't use a merge button. Once CI passes (your changes built on latest develop), then you can click a box that says this PR should merge. An automated process scoops up all those PRs each night and builds them together. The system test team tests that build in the morning. If there is a problem, that is debugged (we build build some bifurcation builds ahead of time to make this faster). Then the batch is merged to develop. This process has worked very well for us. Develop keeps a good pace but is only very rarely broken.