I'd disagree with that - the reps are needed for recoil control and habituation to the noise, etc.
I do practice with a SIRT. In fact, FOF with airsoft and SIRTS are quite reasonable. But we do need the ammo.
A long time ago and I can't find it again, I read a study where they compared training with 22s and transitioning to 38s (similar SW revolvers) vs. just starting the 38s and found no difference. Whether this is true - I don't know and haven't seen it since.
I start folks with a 22 first. Don't want to go off subject, Kathy. Just wanted to respond to the need for ammo.