I don't see how a completely frozen mouse is going to properly thaw in 3 minutes. Adult mice take a good 15-20 minutes depending on how big they are.

Also, there is nothing wrong with feeding on aspen or other substrates. Their stomach acids can break down bone, teeth, keratin, etc. A little cellulose isn't going to hurt a thing.

I feed all of mine live adult mice in their tubs, around 10pm. It only takes me one hour to feed off 70+ mice. Since Ball Pythons are ambush hunters, I leave everything in their tubs and pre-scent the room for a good 30 minutes. This gets everyone primed and ready, so they know what is going to happen. I then have a particular order in which I feed all of them; big rack first, top to bottom, juvie-young adult rack second, top to bottom, and baby racks. There really is no reason to move them out of their home enclosure, and I feel it puts too much stress on them. Stress = possibility for regurgitation. It is also a good opportunity for them to bite you, being that they are in feeding mode before you put them into the feeding tub and then again when you are putting them back into their home enclosure. Doesn't make much sense to me