Replace tubes yearly?

@larsman My new WE 300B's were about 2 1/2 years old, guaranteed for 5 years as you know.  My only backup was a set of cheap Cossars that came with the amp.

WE had a sale in November so I figured buy another pair just in case.

I had no idea mine had deteriorated and the guys in our audio club always thought my rig sounded great.  Much to my surprise, I put the new ones in to break them in and they sounded glorious.  Immediately clear they sounded much better, much more detail at every frequency.  Greater precision in the soundstage.  Not a subtle improvement.

The old ones had about 4,500 hours on them and weren't showing any signs of of their having deteriorated.

BTW, I've had 12AU7s deteriorate seriously within only 9 months.

@dougthebiker - thank you for your thoughts about your experience. It would take me much longer than I've got left to live to run up 4500 hours on my 300B tubes. For me, they get used perhaps 1/10 of that much. 

I think that both bascom king and arny nudel?spelling knew a thing or two about tube's and thier design.they both had thier hands in bhk desidn.i have 2 and have not had trouble.watch the video  from ps audio reviewing them both.alot of prominent audio designers were in the audience.we have a difference of opinion in science that can be good.do your own experiences enjoy the musicand life.

Paul McGowan always says to leave SS equipment on, not tube.  In fact their BHK preamp and power amps are designed to stay on except the tube inputs,  when on standby.  He does say to leave all amps on at least twenty minutes before listening to get the best sound.

The primary reason for leaving solid state on all of the time is because transistors will not degrade nearly as quickly as will tubes from constant use and solid state gear takes much longer to warm up than tube gear.  The primary downside to leaving solid state on all of the time is that this exposes the gear to more mishaps, such as powerline surges and brownout (undervoltage can be particularly hard on solid state gear) and weather-related mishap.  Also, while transistors have a much longer life than do tubes, they are not nearly as easy to replace, and it is sometimes the case that there are no replacement parts available many years later when they do need replacement.  By contrast, most 80 and 90 year old tube gear is easily serviceable.