I like this post. An honest one. My feeling is that there are a fair amount of trumpet players who (like myself) use several mouthpieces and are never certain which one makes the best practice room choice. I've only recently nailed down the best decision for myself. While I'm generally at the very shallow end of the mouthpiece pool I've taken to using my largest mouthpiece for most practice. Avoidance of over training is my most important concern. I'd rather be slightly out of shape than be over trained. So I just run through an easy warm up on my largest m/piece. Then all my harmonic minor scales, some middle register flexibility studies and a few ballads. I do this two to three times a week. All the other days I'm peeling paint above High C on a shallow mouthpiece. And it works well. Had I spent a lot of time practicing on the shallow pieces? Would have felt cramped. No time for the chops to relax and find their groove. By not being over trained the shallow pieces can work their magic. And I'm still confident enough on my large piece to use it on the fly for those occasional "legit" tunes.