Question about valves running hours

My work system is driven by a 55 year old Masterwork amp (by pilot).  I use it for 8 hour work days all of the time and it never fails me.  It does get hot but I make sure it's well ventilated.  If this amp can take the abuse without ever burning up tubes or caps, why can't a new one? 

To further clarify. Like myself I wanted to completely runin the circuit
And left on for 300 hours non stop. My amplifier sits on top of rack 
And heat is not a issue tubes are made to dissipate heat mainly from the Larger input power tubes with no issues,or danger.any quality 
Amplifier has safety circuitry between the digital circuitry,as well as fuse. Good power tubes you should get at least 3,000 hours . My smaller   preamplifier tubes all are Vintage  1950s
Vintage tubes on average at least 10,000 hours possibly much more.
Onot any amplifier brought into the U.S check for U.L approval  . If not it has not been  verified and Electrically approved.if bought on Ebay 
Verify before buying. In Europe EU  approved.in the U.S you cannot Legally sell  without it ,or face $$ liability if something happened !!

Migueca, I do not want to alarm you, but it looks like the Cayin is of Chinese origin?

Several years ago I purchased a Raysonic sp120.
Designed in Toronto, built in China and CSA approved.

Turns out the power transformer was not really rated for 120v

This elevated the heater voltage and caused the tubes to fail early due to overheating. My expensive Gold Lion Tubes failed after 3 months

I did talk to Raysonic, but they refused to acknowledge there was an issue.

I had it fixed for $300 by an excellent tube technician and it sounded so much better and the tubes lasted almost a year after that - played 8 hours daily

I would have the amp checked by a good tube guy - could save you a lot of money in tubes alone.

Now I know some will say a lot of gear is made in China and works fine.
- mine is just one of a miriad of tales about kit made in china that was less than perfect.

The SP120 was my first a last tube amp, so I was pretty green - in more ways than one.

As for the 8 hour limit, I’m with most others opinion, turn off when not in use - you’ll save on hydro

Regards

Williewonka, sorry for your bad experience with that Chinese brand, but Cayin is a well known reputable name. Their products are top notch with lots of good reviews all over the world. Doesn't mean that a product coming out of their shelves couldn't be defective, but lets assume my amplifier is all good.
I guess all of us agree that the major issue when running valves for a long long time (more than 8 hours) it's the excessive heat. And heat is what shortens the life of a valve.
As for having to wait some minutes prior to turn it On again, yesterday someone told me that it is important because of the capacitors (?). It seems they have to "discharge" or dissipate their energy before we connect the amplifier again.
Anyone with a good simple explanation about this? 

Migueca, Glad to hear Cayin are top notch.

Re usage: Tubes have been used in broadcasting 24/7, so using for more than 8 hours should not be an issue in quality built amps.

But to extend tube life a d reduce hydro bill, power down between listening sessions.

And..... enjoy ☺