I don't really care about tube life as long as it's longer than mine. The tube equipment I use operates tubes very conservatively to extend tube life as much as possible. My doctor does the same thing with me.
Don't sell your tube amps
Although this was an article in a guitar Magazine, I thought it might interest those who own stereo tube equipment:
https://www.premierguitar.com/gear/amps/dont-sell-your-tube-amps