Comment by porridgeraisin

I've actually seen this happen before. Most changes get deployed with a gradually enabled(% of users/cities/...) feature flag and then cleaned up later on. There is a slack notification from the central service which manages them that tells you how many rollouts are complete reminding you to clean them up. It escalates to SRE if you don't pay heed for long enough.

In the rollout duration, the combinatorial explosion of code paths is rather annoying to deal with. On the other hand, it does encourage not having too many things going on at once. If some of the changes affect business metrics, it will be hard to glean any insights if you have too many of them going on at once.