I would say it heavily depends on what you do in your CI pipelines, if you only run linters and unit tests, 6 minutes sounds fine. If you run Integration test or have heavy compile times (Scala, Rust?) half an hour to an hour sounds reasonable to.
GitLab’s pipelines run between a few minutes and an hour. We execute pipelines based on what changed. If only docs changed: few minutes, if Frontend or Backend changed, it can take considerably longer (up two an hour).
Please note that this includes heavily parallelized Integration (and E2E) test. This is generally fine because I make sure that linters and tests pass locally for the things I changed before I push.
Also as code review takes quite a while, at least 6 eye principle, colleagues in different time zones, Pipeline execution of time is just something of a minor importance to consider.
I am unsure how many Engineers we currently have exactly, but I’d guess around 450?