I thought the same thing so for working traps I typically do drop sets.

In my opinion I think you'll get the best benefit by consistently switching it around. Doing lower reps will make you stronger, but not necesarily more hypertrophic. That being said, the stronger your muscles become the more reps you'll be able to perform. It all comes hand in hand to me. I could see someone really looking to build muscle doing sets of 20 one week, doing sets of 10 the next week, then maybe doing 1 massive set to 100 the following week. If I had to choose one one of the following sets for hypertrophy... I'd probably go with the set of 100. I'd use a weight you can get to maybe 25 or 30 reps with before muscle failure, give yourself a little break to recuperate, then continue until you hit 100 reps. Pushing beyond muscle failure with these types of massive sets or doing similar exercises with dropsets will make for great hypertrophy.

Just do both and play with muscle confusion

It's mainly about putting new stress on the muscle that you are working. Whichever way you do it with more weight or a high rep range with full range of motion (or close to) you should be struggling on your last reps.