Well, you switch to get your sound right. I'm a long time player who took a ton of time off and came back to a high wire act of an embouchure, a lower lip tuck that was suggested by a former teacher of some repute, and back in the day, after suffering through months of adjustment to get my sound, I never knew why he did that since I wasn't a music major and didn't practice enough to make any embouchure placement work. Plus, I was overblowing anyway!
After coming back, I slowly went back to a virtual einsetzen position, immediately got a sound I wanted and spent a couple years getting the kinks out and concentrating on fundamentals, particularly air. Pretty happy with it. As for going back and forth with different instruments-- I do play trombone and dabble in French horn-- yes, it takes as much time on those slightly different settings and mpcs but I'm putting in that kind of time now.