I wouldn't say there are any rules, just try different rep ranges for each muscle and see both how you respond and how it effects you in terms of injury risk, since lower reps and higher weights can lead to injury. You'll definitely gain size on any muscle on any range from moderate 6-12 to higher 12-20, as long as you add weight or increase reps/weight over a period of time.
One advantage to keeping the reps at least 10 or higher is that it reduces the risk of injury. That helps alot on leg work where the strains on the joints are higher due to higher weights used.
Also i think it's better to keep the rest between sets 1-2 minutes tops, because that will ensure that the area worked stays warm, thereby reducing injury risk. Not only that, it's more mentally involving to keep the pump and metabolism going.