Trouble is mark. In the wild they will eat what ever they find, think of a redfoot that finds a dead bird, it will eat every part of that bird, another redfoot may not find one for months, mother nature combats that with humidity and rainfall. Must do!!!!I would still advocate a relatively low protein diet. I referenced protein earlier in regard to keratin production, but agree with @DPtortiose in that it doesn't take much. I was referring to a few times, years ago, out of frustration, I kept trying artificially lower and lower protein as that was promoted as a cause of pyramiding. It didn't work - they still pyramided.
The more I learn the more I stay to the belief that the keratin and scute formation is pretty even and uniform, and once laid down, stays that way. So would resist the idea of more protein = more keratin / thicker scutes. Wear changes that, of course and we see old, wild tortoises with extremely worn scutes.
Yes I agree, once it's layed down it stays layed down. After let's say a hatchling is a 6months old the bone structure is set, it will follow that set path. This falls in with they hatch in monsoon season. Think of the bone structure as a tree branch, you can train it when young and supple but once it's hardened off it follows the path you set it on. After the bone structure is set, the keratin will follow if what you are saying is right about keratin being pretty uniform.