Soldato
It doesn't have to be less weight necessarily it depends what you can handle.
I'm a huge fan of dropsets yes - a good way of recuriting fibres.
I can get to the end few reps of the last set and actually not be able to move at all, so i drop weights so i can keep the movement, or il will finish the 2nd set of 3 and have to do the last set with a lower weight, i do it so i keep the intensity of the sets, just lower the weight so can actually complete the movement