When I'm doing my leg lifts and such, I generally do about three sets of 15 reps. I usually do them with a bit of a break between each set to catch my breath. But when the gym instructor has me do them, he usually keeps me going with little rest. As a result I'm only able to do about 15 reps in all.

Just wanted to know which way is more effective? Going at it full steam and ending up doing fewer repetitions? Or taking my time and doing all the sets completely?

Thanx

Most trainers will have you do sets with a rest period in between. That gives you the opportunity to build maximum strength. 3-5 sets of anywhere from 5-15 reps, just depending on the program.