I'm afraid your mistaken my friend. You should get involved with the National Team so you can educate yourself on how to train some great players. Powerhouse singleposition training coupled with training JS and 1v1 at the Guard position is what has made players like Joe Bronson
(7929116) absolute studs. After learning what I have learned from the NT I would have trained more 1v1 at the guard position.
Training Handling does add OD to the same effect that 1v1 trains JS but it also trains Driving at the same rate that Driving itself trains Driving. Therefor your point that Ha is better since it concentrates on "more important" skills is moot. It comes down to if you want your player to grow faster in JS or OD. In the end the combo of JS and 1v1 will make him fly up in the JS skill, while saving time and allowing more weeks to train Driving and Ha. I would suggest you message Bronson's owner, ChewBrian, or Coco for more insight as they have been a fantastic asset to training my guy.
Note: I'm not arguing with your point that JS trains JS best but in a training regime you need both JS and 1v1 at the guard position, and is in no way harmful.