As far as I can tell, Combat Training doesn’t spend points. It’s simply one’s choice whether to boost it to Confident or not. We’re probably not all going to min-max, so I don’t expect everyone will boost as high as it goes just because they can.
The sub-modules can probably be increased through play, just like the rest of the modules. And it probably doesn’t relate to number of one’s rank, or Minor and Major modules, since those are point related.