I think it depends on your goals. You also don't want to do the same routine forever, change it up periodically. It sounds like what you are doing is 4-5 sets at the same weight. How long have you been doing it that way? Last spring I switched to a pyramiding routine, where I start with 12 reps of a particular weight, then move the weight up and the reps down to 10, then up the weight again and do 8 (or as many as I can up to 8). This was new for me and I have seen great results as far as muscle gain.
-------------- ~Victoria~
...There are no shortcuts to any place worth going.--Beverly Sills