You're not alone, can confirm everything you just said xd sucks tbh.. changing sens is like a drug, addictive af... and no, those "perfect sensitivity" videos are bullshit, for me at least. tracking a frozen bot i can do with any sens, but once the target moves its different. And when you've got a "decent" tracing sens, the problem starts with flickshots and sure this is where muscle memory comes in play but that wouldnt matter too much if you're wayyyyy off your "natural" sensitivity.. because no matter how much you play and practice that sensitivity, your muscle memory will only develop to a certain grade.. but what do i know, that's just my theory altought i was a veryyy good aimer before i started to change sens every day xD