You can’t lift too heavy or too light
 

There is no doubt that you can*build mass on heavy weight*and lower reps (1-5) but the load needed to gain mass on a low-rep program is difficult for the most of us.
Unless you have a 400-pound bench press, 500-pound squat, and 600-pound deadlift, you will need some more reps.
In order to cause enough stimulation for muscle growth, you need to have a higher time under tension (TUT) to cause enough microdamage to the muscle tissue.
Conversely, if you train too light (15-25), you will not have enough load to stimulate strength in the long run.
Different rep ranges on occasion help to break up the monotony but with proper nutrition and recovery, the 5-10 rep range will be the perfect prescription to gain mass.

I think you need to try different rep ranges etc occasionally to stop the brain dying of boredom, not just to keep your muscles guessing.

Another good post, Eazy :D