For me 100 reps means not putting the weight down until the sets over, and I enjoy doing this at the end of my workout. If I have the energy I will do this at the end of every workout. Curls, facepulls, and front raises are a given, but abs, hams, and calves are easy to squeeze in as well.
Right now I'm trying to catch up my shoulder's so I use this for latterals 10-20lbs and don't set the weight down till 100, I cycle through front, side, rear till I get 100-20 front-20 side-20rear than back to front, this way I don't really have to rest, but the pain is unreal. I don't like doing much isolation stuff, so this works great. finish your squat, bench, or deads, then pick an exercise for your weak area say hams, do 100 leg curls, or GHR and go home.
I think it would work on pretty much and isolation exercise, and some compund lifts. The problem with the compounds is the weak link wears out first, wheather thats a problem or not I don't know. Latter