This is a situational maybe. In South Florida especially during hot weather in densely populated areas we experience fairly large voltage fluctuations. During peak demand hours at my location voltage can range from ~105-120 VAC. Power tubes were constantly needing to have bias adjusted. Like weekly. I bought a power regenerator, originally a PS Audio P10 later a P20. Tube bias requirements dropped almost to nothing, like once every 6 month I check but almost never need to adjust, and tube life at least doubled. So if you live in an area with high peak power demands and consequent voltage fluctuations taking steps to regulate your power supply could extend power tube life.
