I don’t have an answer to OP’s actual question, but I thought I would restate it since so far most have answered other questions instead of what they asked.
What duration of time left on is equivalent to the wear of start up for tubes?
If you leave the room for 5 minutes it clearly makes sense to leave your tube equipment on. However, if you are done for the night and going to bed and probably won’t be using your tube equipment for 12 hours it makes sense to shut it down. What about the times in between? Most days I can listen for a little while in the late afternoon and then again late at night. For that average 2 hour gap I wonder exactly what OP asked. Do I leave it on or shut it down? I usually turn off tubes but leave on SS. I’m sure it would be heavily tube and equipment dependent. Some tube types are more tolerant to startup and some equipment is kinder.
What duration of time left on is equivalent to the wear of start up for tubes?
If you leave the room for 5 minutes it clearly makes sense to leave your tube equipment on. However, if you are done for the night and going to bed and probably won’t be using your tube equipment for 12 hours it makes sense to shut it down. What about the times in between? Most days I can listen for a little while in the late afternoon and then again late at night. For that average 2 hour gap I wonder exactly what OP asked. Do I leave it on or shut it down? I usually turn off tubes but leave on SS. I’m sure it would be heavily tube and equipment dependent. Some tube types are more tolerant to startup and some equipment is kinder.