Thanks for the thoughts folks. At this point, getting my lifts up isn't helpful. I can't argue it might help in general but I'm adding only small amounts each week.
As to why I think it is both the challenge and Rip's view there there is no 'strong enough'. And yes, I can pull a 70 lb bow...but as you say it isn't steady at all. My train of thought is if I can pull 100 lb well, I can hold 60 lb more steady than I can now. Just like lifts, at some point what used to be hard is now my warm up. If my work set is 100 lb, then 60 lb should be trivial.
Bobman, good point about not shooting every day.
Also, there is this amazing feel about flinging arrows with a heavier bow that is not unlike the same feel we get moving heavy weights.
I'm going to toss about again the question about static holds. I'm curious people's experience with that if any and although not as efficient as a load increase, will it help in theory and practice?