>> You want PRs because they help others absorb what you’re doing

That isn't really where it came from though. The idea was, if I want an open source maintainer to accept my changes, I make a request to pull them from my branch. Once the open source maintainer has merged it in, they own it. If they don't like it (even one little bit), they can reject it because quality / ownership / maintenance is completely on them.

On a team environment where no one owns anything it is a little less clear what the value is. You want to incentivize the "betterness" of "something" and are using "broadened knowledge" as a proxy for that. Usually this just goes unexamined but really it would be good to establish how broad and deep you want this knowledge to be and work back from there - is the 5 minute PR review the best way to achieve it?