Cutting players later, adding later?

Do HS baseball coaches cut kids due to skill shortcomings after the season starts, as opposed to just benching them?

What about adding a kid to the team later? Say, two catchers are injured or transfer schools. Can coach grab a kid mid-season who used to be a pretty good catcher but didn't go out that year? I believe our state requires players have a 2-3 weeks practice with the team prior to going into a game. Still, there may be situations when adding a kid later would be helpful.

I've never seen either circumstance occur.