From experience over the years, the 8-12 recommended for beginner's will work for a while, in both of the lifts. However, from what I've personally seen, the guys/gals into bodybuilding usually go with higher reps (10-15 range) in the squat, as they seem to believe the higher reps are better for hypertrophy, and Stay with a moderate to moderately heavy weight They also stay below or at 5 in the deadlift (if they even do the bent leg variety). but usually go with the higher reps again in the sldl movement, again for hypertrophy. It's also a great conditioner. The all out strength approach is to stay 5 or below in the squat
Personally, I like Bill Starrs approach, heavy-med-light conditioning. On heavy day work up to a 3-5 rep max,work up to 80% of that for 5 reps on a medium day (if used), and light day is 5X10 with a lighter weight, 1 min rest between sets. Kind of splits the difference.