Delt trouble

On most exercises I need to drop the weight 10% to complete the same number of reps.

However while doing seated dumbell presses I lose 20 percent or more per set !, any thoughts of the cause of this ?

This goes for overhead presses only, on lateral raises and movements like the bench press or squats or whatever I dont have this problem.

What are your rest periods between sets? I know that when I’m trying to add size (strength), I give myself 2 - 3 minutes between my heavy sets (and do very few sets), and sometimes I can even get more reps on later sets (as I get more focused I guess?).

Rest periods are 3 minutes.

How many reps are you doing in each set? If you’re like me, maybe you’re doing too many. I’m finding that singles work best for me. I remember when I was doing sets of mmore than 5 I wouldn’t be able to do more than one set with a certain weight, but I can do up to 15 singles.