I bought bags of river stones from Ikea and B&Q and a tube of aquarium sealant and made loads of caves with them. (If you do this, make sure the stones are boiled up forever and a day to kill off bugs and clean them up, and when you create the cave make sure they are extremely well attached and check them frequently for loosening of the stones. After about 3 years I found a couple of the stones were wobbly and resealed them)
The axolotls have the choice of being out in the open at the front, or hiding in the caves and under plants.
Not surprisingly they spend most of their time in the caves, or lurking in dark corners.
This suggests to me that given the choice, they will choose a small dark place to hide, so yes, providing hides will give your axolotl somewhere to go to be secure, hidden, or whatever it is that motivates them to tuck themselves away.
When I bought my first axies all those years ago, I wanted to buy some logs and hides, but the woman said 'Nahhhh, don't buy stuff like that or they'll hide away and you'll never see them'. That made me MORE keen to buy them hides, as surely if they want to hide, you should provide them space to hide!
