Eventually we all plateau on every lift. I've often just taken that as a sign that it's time to change exercises / routines / my point of focus / etc. but it strikes me that when the lift in question is one of the big compound lifts it might be more beneficial to identify the weak muscle group(s) and bring them up to speed rather than changing up the whole program.
E.g., when I hit a plateau on the bench a few weeks back I decided to test my theory that I was torso-dominant and that it was likely my arms that were holding me back. So for a month I started every workout with two tricep / bicep 5x5 supersets and incorporated drop and double-drop sets on each exercise as well. I otherwise kept everything at maintenance levels and didn't change anything. After four weeks of busting ass on arms I returned to my previous routine and was quickly able to add 10% to my normal working weight in the bench.
My question is: how in the heck do you identify which muscle groups are holding you back in the big compound lifts? It seems that a bit of equilibrium is probably a pretty efficient way to push one's working weights up but I for the life of me have no idea how to accurately identify where I need supplemental work. Anyone?