A couple of things you need to take into consideration:
1. When playing a small/medium pair you don't always know if your opponent has a bigger pair or a big ace (where you are a slight fav). Thus, you need to make your calculations based on their range, not a specific hand. For example, if you think your opponent has either AT+ (64 ways to make these hands @ 16 ways each) or a pair (72 ways to make bigger pairs @ six ways each) and you have 22, then you really can't exploit the fact that you are a favorite over the big aces.
2. Also, you reasoning works better for cash games than tournaments, as you have to consider your real money
equity (vs. your chip equity) when deciding to play a hand in a tournament. In other words, if you lose your stack in a tournament you are out, and have zero actual equity. So you may want to find a situation where your "chip equity" is a lot better than 5%, since losing this race can end your chance for actual dollars. If you can "pick your spots" where you get the money in as a 70% or better favorite instead of a 5% favorite you will be better off long term.