This is one of those questions you see a lot and you get all type of answers, with mostly people trying to apply common sense to the question, sometimes in chemicals common sense don't apply.
Test from years ago with an adhesion tester proves the following:
To keep it simple we will use the epoxy.
Single stage applied over epoxy that had one coat and sat two hours.
Single stage applied over epoxy, that sat 24 hours at 85 degrees.
Single stage over epoxy that sat 30 days and one panel scuff with 400, another wit 800 and another with 1000.
The tests were full adhesion on all panels with no readable difference.
Base coats would very as far as wet on wet as some bases have better adhesion the others, that is why when people call about using epoxy as a sealer I ask color and brand of base as well as temp and give different answers, for wet on wet.