Adding banded tension to your shoulder work is guaranteed to trigger new hypertrophy gains. Just grab a couple of resistance bands and wedge them under the bench for overhead dumbbell presses.
The key is to lift the dumbbells all the way up to the top and hold them there for a couple of seconds in the contracted position of each rep.
With mechanical drop sets, instead of reducing the load, you switch to a new but similar exercise by changing the grip, angle, etc. The result is a whole lot of burning and a whole lot of growth.