There is no magic potion .. if you want to run 2 defenses, you have to practice 2 defenses. You can have 17, 17, 17 (which is 51) and practice the rest in normal development. Or you can do what you do, and only play press (with 10 minutes of practice) at certain times, etc.
Either way, there is no shortcut .. if you want to play 2 defenses, you will either need to have defensive IQ grow slower, recruit only guys who run at least one of the defenses, or have attributes grow slower and put more time in defense. It's math, it only works one way.