there are a lot more things to consider preflop than just your equity. this is because the effective stacks are deeper than on later streets, and this means that positional advantage and skill advantage become slightly more important (than when the effective stack is more shallow compared to the pot). on your question of using equity calculators in your hand reviews to help your in-game i will just say this: if you practice forming a range for your opponents based on their actions, and you begin to train yourself to get a feel for what your equity against that range would be, you will be doing a very good thing for your poker game. fwiw, developing that "feel", at least in my experience, comes from studying/reviewing hundreds of hundreds of hand histories and continually estimating (and checking in stove) what your hands' equity is versus a hand range.