I don't do compound movements like dips, close grip benches and skull crushed (with barbell) those did nothing for me.
I have gotten serious growth this year by actually doing isolation (as isolated as I could get them) type movements. Cable work. Dumbells. Push downs variations, etc... what you have to do is make sure you lock out on each rep. If you don't lock out, you are not getting full benefit. Also, I don't think anything of doing about 18-20 sets for just triceps.
Sometimes I go in and do 2 sets of as many exercises I can fit into 35 minutes. Rep range is irrelevant. I will start with pushdowns, 2 sets, then move to dumbell extensions, then reverse pushdowns, then one arm cable pushdown, over head rope extentions, behind neck one arm extensions, kickbacks, etc.. just as many as I can get.