yea, as stated above, its what works for you.
I tend to add weight, but I dont really go to failure except for one or two reps of each exercise. I do 2-4 warmup sets for each exercise though to get my body acclimated to the weight I use.
Like leg press, I'll do 2 plates per side for 10 reps, then 4 per side for 8 reps, then 6 per side for 6 reps - but not really pushing too hard. not enough to be using up my energy for the working set. The 'working set' is usually 8 plates per side for 8-10 reps.