Doesn't have to be 20fps, I only use 20fps if I know something is going to happen which will benefit from it - which hasn't come up for people shots yet.... mostly shooting 5fps.
I'm shooting a rehearsal for a play I've never heard of, it's extremely chaotic - things happening all over the stage simultaneously. A girl is grabbed and pushed and she throws a bunch of plates into the air as she falls - the AF instantly locks onto her and I grab 5-10 shots and one of them is a winner.
There's a short chaotic scene of dancing all over the stage followed by them diving to the floor as a pair of 'police officers' enter view at the side... shutter burst gave me a great usable shot of them diving with the police in the backgrodund
Compositions and creativity were not compromised..