I agree with Michael Fooks about not telling beginners to change their ukemi when a technique isn't working. Usually, I find that it is a much better to work on changing my own technique to adapt to the difficulty. In fact, not too long ago I had a beginner spinning out of shihonage, and after trying several changes to my technique, I finally figured out the key to preventing it. However, this was an isolated case, and if Drew is having this problem "almost every time" he practices with beginners then I suspect there is a deeper problem that he needs to work on in his technique.
OTOH, there are aspects of ukemi specific to techniques that should be taught, and for shihonage the principle of keeping the hand close to one's shoulder is often one that comes up for newer students. However, this point is solely for the uke's own protection and not to cover up deficiencies in nage's technique.