Heat is the enemy of electronic components!
That old 'leave tubes on all the time' folklore dates all the way back to the 1940s when the first computers used had about ten thousand 12AX7 tubes packed in banks and banks of interconnected circuits. Back then,if they turned this monster off, they were nearly sure to loose a couple tubes at the next turn on and have the terribly job of finding the failed tubes in the forest of hot glass.
On all the time wastes energy, eats up the service life of all the parts, and serves no useful purpose. We have yet to see a field failure of a tube in a Fet Valve CF preamp. Turn on is slow and gentle by design so please just turn the equipment off when you are not using it.