I've seen strong squatters with their hands everywhere from 2 inches outside their shoulders all the way to the edge of the bar. Personally, I put my hands all the way out on the collars of the bar. That allows me to distribute the weight of the bar all the way across my upper back. It's far more comfortable to me, but certainly isn't for everyone.
Current PRs at 242, raw w/ wraps- 525, 355, 605, 1485
Roboro tui, perimo vester adversarius
(Build yourself, destroy your enemy)