The rule of thumb I've always used is to "put a smile on them". Always double check that the bit is resting in the center of his bars as well. If he has been handled roughly for a long time and you suspect "bit abuse" then a little tighter or looser should put the bit in a new place - just be sure it is not hitting teeth.
I think 2 but I have never really counted wrinkles. I always just adjust until it looks right.
Yep.
They are all very different so number of wrinkles can be different. I have 1. Kinda. They both prefer the bit to be little loose, so if I go to 2 they shake the heads.
I go by how it fits/rests in the horses mouth. No wrinkles for Walka.
After putting the bit in the mouth, put your finger where the bit is resting to see if it is hitting any teeth or resting comfortably in the bars. Adjust accordingly.
I go barely a wrinkle My horse has a very soft mouth. I figure if you start with the bit in there too tight to begin with, he doesn't have a chance to respond to a lighter aid. Doesn't seem fair to the horse.
Wrinkles do not matter. Every horse's mouth shape and conformation is different.
You need to LOOK inside the horse's mouth when the bit is in. The bit should lay right in the middle of the toothless area in their jaw. If it's too loose or too snug, it can bang on the teeth when you ride.