If I were you hopson I'd just switchoff between ID, IS, REB, and maybe a little SB for the next season or two. If you only train one skill, the elastic effect will come into play, and training will begin to slow down. I'll further explain this:
The Elastic Effect:
As certain skills increase, the lower ones kind of weigh them down for say. The more and more you train higher skills, the greater the weight becomes, and can eventually lead to pops in random areas.
So basically because there is so much weight, once you train the lower skills they tend to train rather quickly, but if you train the skills that are superior to it, that skills training speed will slow down significantly.