How many sets/reps for?

to add muscle mass on myself how many sets/reps should i do. i have always heard mixed ideas. for about six months i have been doing - heavy weight- for example. flat bench- 100-110lb dumdbells 2sets-4-5reps - incline-85lb 2sets-4-5reps decline-85-90lb 2sets-4-5 reps. some guys say that thats not enough to make any gains and to easy to hurt joints if you can' get atleast 6reps its a wate of time for size but not strength training. do you agree? i did this workout setup on my cycle last summer and i put some size on everyone was like holy crap.. whether just being on the juice would have made me big whether i lifted that way or with more sets and reps i have no clue. i want to know the best way to add SIZE..

I am on a lean muscle mass diet and change my routine possibly some what similar to what your goals are. IMO at least 3 sest are need for optimal size for ex. ill do 3-4 chest excersises ill usually do between 3-4 sets sumtims 5 for flat bench press then I go real heavy rep ranges are usually like this 10,8,6,4. Hopefully this thread gets some more opinions though

alright- cool thanks

I started a really good chest workout I got from a thread here. I do about 1-2 warmup sets, then it is as follows.

1 set-6 reps
2 sets- 5 reps
2 sets- 4 reps

I only increase the weight every time the reps change, so three weight variations. By the end, I usually need somebody to pick the bar up off my chest. Although it really doesnt burn/pump me that day, the next 1,2,3 days even are hell.

The next workout consists of even heavier though, it goes:

2 sets @ 3 reps
2 sets @ 2 reps
1 set of negatives @ about 4-5

Go really heavy, to the point where the last rep is failure, or barely getting it up.

Hypertrophy varies, but between 10-15 depending on muscle worked.