Oh nice, that's actually pretty smart. I usually just spray them with coolant but that runs out fast. A wet towel would be way cheaper, you could even keep a couple in a small cooler. Gotta make sure it's just damp though, too much water might not be great for the blades long term.
Noticed this a lot lately. People finding simple fixes for small problems. Like using a binder clip to keep a phone cord from falling off a desk. Or a bit of tape on a wobbly table leg. @iris_adams is right about the damp towel, it's that kind of hack. Just using what's already around. Makes more sense than buying some special product for every little thing.
Funny thing with that damp towel trick, it reminds me of a friend who used to keep a wet rag on his toolbox during summer to keep his sodas cold. He'd just drape it over a few cans and they'd stay cool for hours. Not the same thing exactly but it's that same kind of low-tech thinking. I tried it once on a road trip and it worked way better than I expected. Whole different use but same idea of using what you've got.