@invalid good point that not all tubes need be top performers. It all depends on the specific design of each amp.
I had a ARC sp16 tube preamp that used 6 12ax7 tubes. Only one or two required very high performance tubes. When I bought tubes from ARC, 1 tube always cost more and was designated for use in a specific slot. The others cost less. If I heard noise I would swap out the bad tube but keep it as a spare in that it could be perfectly fine next time. I labeled my used tubes in a hierarchy so I would know which ones sounded best still when removed and would always try that one first. My stash of spares that were removed prior kept me going nicely for many years. That one slot that required the top notch quality tube was replaced just once with a replacement purchased just for that from ARC. Just an example. I’m sure every tube amp is different. There may be cases that require all tubes be replaced once a year. Some amps are harder on tubes than others. It all depends. Tubes can be quite cumbersome and expensive to maintain, especially if there are lots of them, which is something I have always tried to avoid, but of course different strokes….