For me, one advantage in holding rather than snap shooting is that once I get to full draw, I can run through a little checklist of things. One of the things on the checklist is to check that my string forearm is relaxed, because it generally picks up a little tension in the process of drawing the bow.
Of course, for the checklist to do you any good, you have to be able to feel the difference between your forearm being relaxed and tense. If you don't know if your forearm is relaxed or tense, I would suggest spending some time in front of a blank bale focusing 100% on your string forearm, until you gain awareness of whether it is relaxed or tense.
Or, as Arne recommended in a different post, get yourself a Formaster, that will force you to draw with your back, because it takes your forearm out of play. It doesn't exactly teach you to be aware of your forearm muscles directly, but it does teach you to be aware of your back muscles, which is really more important.