u can thank me later, but here is the key to hamstring training.
For hamstring hypertrophy, do low reps in a leg curl machine and higher reps in stiff leg deadlifts, Romanian dead, reverse hyper, and back extension. The reason why is because when you're working your hip extensors you're also working your glutes and erector spinae and those tend to be higher rep muscles. In other words, if you're using the leg curl machine you should be using eight reps or less. Someone with a higher training age may only need three reps, but use a higher amount of sets, like 10 sets of 3.