You can probably get better results with 12-15 reps. That way you can keep the weights relatively high and continue to stimulate muscle growth. If you go to higher reps it becomes more of a cardio (or aerobic) exercise, meaning that it is building your over all ability to absorb oxygen and transport it to the muscle cells, rather than stimulating the individual muscle you are exercising.
That said Tom Platz claimed to do 100 rep squats the last few weeks before a contest and arguably had the most unbelievably cut thighs ever seen.