Even during periods that I am building up, I still find myself sticking at a plateau level for a bit of time before I try to push myself to the next level, so there are times when I already know that I can do a higher level of sets or a higher level of pushups per set, yet I may well decide to purposefully hold back in order to allow my body to adapt a bit better for some lower quantity of sets and/or pushups before I have the day that I end up doing the higher quantity.
I believe that's the better way to go about it expecially when it comes to doing exercise, maintaining a stable level before going to another level gives you a high momentum and strength to push above your previous limit which the body has adapted very well before breaking to another level. Most of the things we do here sometime required experience and high level of professionalism to do better.