I'm not sure what set up TTG use, whether they have spare masks or not. I would assume so.
Numbers, sure servicing your BA mask when you get home from a job is fine but we are volunteers and anything that makes our lives easier is always appreciated. If have a drying cabinet and spare masks means getting back to bed 15 mins earlier at 3 in the morning then perhaps it is worth it...
In our brigade we have considered getting a larger unit to do PPE in as well, we're just considering all possibilities...