If you're training 1pos for ID, you should expect to get to somewhere in the respectable-proficient range this season if that's your only training, but I agree with rotating in some kind of training other than that some. Something I'd like to suggest is to rotate in a week of 1on1 for forwards after each ID pop (just one week, then back to ID), because it would improve his Handling, Driving, and Inside Shot. At the cost of ID only reaching the Mediocre-Strong range on the season (depending on how strong the elastic effect is, I'm not sure entirely), his Handling should at least get from pitiful to inept, I'd hope, and driving to respectable or even strong coupled with potentially a pop from respectable to strong on IS and a pop from mediocre to respectable in JS, I think it would be worth it for the offensive capability he'd gain.