I actually tried the hundred pushups schedule about 5 years ago, I believe I got up to where my single-set max was about 50. But I definitely plateaued, I don't see how I could have gotten to 100. Also, my shoulders got really sore all the time (joints, not muscles), I learned afterwards in order to make things easier I had my hands spread way wide, and that incorrect form was bad for me. That's why I'm trying to do them with hands closer now. Not diamond, but like under the shoulders instead of under the elbows.