The tubs on the rack I have there has small feet on the corners, so I actually just placed them where the feet weren't. Theyre the Container Store tubs for the AP rack. So I have no wear at all, but for a flat bottomed tub it may be different and cause wear over time. I imagine it wouldn't be too bad, though. They are written on with Sharpie, but I don't have any experience with tubs rubbing on them to make a guess at how fast it might wear.
I doubt that tubs would damage the label itself any faster than they do the tape to hold down heat tape, so that's not likely to be a problem. And if it is, they're fairly inexpensive to buy if replacing became necessary a few years down the line.
Since I have 3 different thermostats, I just label them H2#_ (Herpstat 2), H4#_ (Herpstat 4), and RL2#_ (Herpstat 2 Red Line). With the blank for which probe. It saves space since the labels are small on my individual cages. I do tend to write it out fully if I use a dedicated label on a rack and I mark which tub shelf has the probe, in case I forget.
Sent from my SM-G950U using Tapatalk