I've come across an idea that as I observe I find more validity and reliability in it.
Here's the hypothesis:
The most optimal placement of a trumpet mouthpiece is to have the top and bottom portion of the mouthpiece touching the upper and lower divits. This keeps the mouthpiece out of the red and the vermilion border (the ridge that separates the lip from the face) possibliy serves as an anchor that keeps the mouthpiece stable. As for individual differences, that can be seen in jaw placement, dentures, and angle of the horn. However, the divits are touched by the mouthpiece and possibly the vermilion border helps anchor the mouthpiece so it doesn't slip around.
I've looked at scads of pinterest images of famous trumpet players and other images on the internet and the hypothesis seems to hold (at least for the divits). Also, for many that I've spoken with on this site, when a person gets tired, one of the first things to give way is the lower lip which slips out of position. This is remedied by firming up the bottom lip by possibly curling slightly or whatever is needed to get the bottom lip back into position.
Here's what I'm thinking. There may be a universal placement which involves placing the mouthpiece on the divits and the vermilion border helps anchor the lip against the mouthpiece.
Here's the test:
Please go to a mirror with your mouthpiece and watch yourself buzz (it will take less than a minute). If what I'm saying holds true enough times, then children starting out can be taught to place the mouthpiece on the upper and lower divits ( I don't mean curling the lip in so much that the red disappears) but slightly curling the bottom lip or simply tightening the lip so the mouthpiece touches both divits. I know it's easy to just report but please try it out with a mirror before posting your result.
What does this possibly have a future effect on? Mouthpiece size. Possibly the distance between divits will be a fair measure of the mouthpiece size required.
Thanks so much