If you work on improving your speed then the qualifying rounds become easier because you’re running sub max. If a 22.6 guy needs a 22.8 to qualify for finals he’s running all out and will be much more tired for the final than a 22.1 guy who cruised through prelims.
And to be honest butting your head with the coach isn’t going to help anyone. If your coach is open to suggestions that’s great and by all means bring up some things for him to think about. A coach needs to believe in what he’s doing and the athletes need to also believe in it. If either party doesn’t believe in what they’re doing it’s a no win situation.