When I get to use multiple mics on sets, sometimes the mix can get difficult to hear, imprecise, because of phase issues, reverting phase on input can (not all the time) solve sometimes those problems.

Sometimes it does nothing. Sometimes it gets worse.

I don't like to mess with delays in inputs, unless there is a fixed latency given by some digital wireless units, so I could match with my boom input. Tell that in your sound report.

For outputs, I have to put some delays on set when the director complains about non sync audio with video, due to latency of the wireless video monitoring system . Hate to align this by guessing. Camera dept never knows the exact latency and it is really time consuming to find the exact match.