Question about valves running hours


I'm new to the tubes world and when I bought my amplifier the seller told me not to run it for more than 8 hours, letting it for rest a couple hours before the next listening session. I wasn't told why, but now I got curious and I want to know more about it. 
What's the reason for this limitation? What can we damage and why?
128x128migueca

Showing 2 responses by rodman99999

On/off cycles are much harder on any electronics, than hours.   Outside of heat, a tube's biggest enemy.   
On/off cycling during listening sessions is ridiculous.   Absolutely turn off tubed gear, when not enjoying your music.   I didn't mean to imply otherwise, in that first post.