Mixed routine?

[CRAZED818]

I'm an ectomorph and it's recommended that I follow the 5x5 workout program. I know 5x5 = lift heavy, low reps. Here is my question - if I go real heavy, I can't complete the 5 sets. So, I've been lifting enough weight so I can get in 5 reps in 5 sets. However, I don't feel like it's working my muscles out that well as opposed to doing 3 (or 4)x 8-12. I've actually mixed both programs together. For instance, let's say I'm working out my bi's. I will do 3x8-12 at a machine and then 5x5 with free weights...is this okay? Should I stick to one routine? Also, how many sets do you usually do for a certain muscle? I usually do 7-8 different exercises for each muscle ...i.e. 4 free weight exercises for bi's and 4 machine exercises for bi's? Am I overtraining my bi's? How many different exercises should a person do for a certain muscle? By the way, I'm a beginner.