I wanted to mention this to you also, since you said your son was not on a pump. Is he using pens? You don’t have to be limited to 1 or 1/2 unit increments!
I use a pen for 1/10 unit increments, particularly when exercising.
Take a look at my comments on this post:
back-to-mdi
All you need is an extra pen, and insulin diluent.