Just checked out old German. Pretty sure we ain't building a MATCH rifle.
1-10"
I know German. I"ve shot with him at Perry.
I respect him.
There is no way in HELL I"d twist 11 when I could get 10. You just leave too much on the table with an 11 IMHO. I've seen 11s not stabilize 190s well enough.
I run a 10 Rock in a 308, and it runs 185s fine, and I suspect 210s will be no problem if I ever play with those.
a 12 is certainly out of the formula.
You can overtwist I guess... but running .224 bullets in a 6.5 twist 223 Rem, 20 inch tube, I could still shoot 52 smks at sub moa at 200 yards and about 3300 fps or so IIRC. And not toast them. Varmint jackets didn't fair so well at times... but the twist did stabilize 90 jlks.... very versatile.
IE you won't be unhappy with a 10.
The only way I'd shoot a slow twist is if it was a short range 200 or 300 max yard BR gun, and then I'd twist to the EXACT bullet I'd be running and no more at all. But thats a specialty gun and setup.