I know A-B-A same day works fine as long as there is no overlap. But you cannot have two flights that have either the same origin or same destination on the same calendar day. So A-B-A-B-A is subject to cancel bot according to the current CoC. Can't have two trips of A-B and the other another A-B or A-C same day either.
I've had A-B-A-B-A flights in the recent past and they didn't get cancelled. None of the flights overlapped and the flights were short, so there was plenty of buffer between flights. I believe nsx has mentioned doing 2 roundtrips in a single day earlier in the thread too.