I haven't a clue where you read your information,but it's flat wrong.

Most people will tell you the whole point of a Standby switch is to allow the heater current to the tubes and let the tubes warm up before you hit them with full B+ voltage (which is what the Standby switch turns on and off).  The theory is cold cathodes can be stripped over time by the high voltages.  So, the procedure is to turn the amp to standby, turn the amp on and allow a good 30 secs or more for the heaters to work before turning the standby off and applying the B+ voltage.  There is no optimum power down procedure, because there is no plus or minus to turning off the B+ voltage before the heater current. 

However, as many long stated facts in the guitar world, it seems this is pointless.  The idea of Standby switches saving tube life by preventing cathode stripping was discarded by  the hi-fi world over 50 years ago.  It's very rare to tube hi-fi amp with a standby switch (though some modern high-end equipment will have slow ramp up circuits).  And all tests to try and prove cathode-stripping of cold tubes has come back negative.  There is NO laboratory evidence that using a Standby switch or not saves or kills tubes.

But chances are that's NOT why they added them to tube guitar amps.  The Standby switch is on a guitar amp so that you can turn off the high B+ voltages between sets.  It is called STANDBY because that is exactly what it is there for...when you aren't using the amp, but aren't ready to turn it off. 

So, common believe is Standby's are on tube amps to preserve tube life, though they probably don't. They are really there so you audience doesn't here 60-cycle hum while you take a piss break.  But they definitely DON'T hurt the tube amp.  And they are almost exclusively used on tube amps. 

Now, for those who believe in cathode stripping, the 5V4, 5U4 and 5AR4 tubes rectifiers offer slow votlage ramp up, so a Standby doesn't have to be there because the rectifier takes a while to deliver full B+ anyway.  But the 5Y3, like on a Champ, well, that's a fast ramp up tube. 

Pure and simple what you should take away from my thread.  Standby is great if you play live, because you can put your amp in standby between sets keeping your tubes warm and avoiding subjecting your audience to the possible loud pops as filter caps discharge when you turn off.  It is what it says it is a standby switch, not a power up/down switch. 

If friends are actually electronic experts, they wouldn't see the point of a standby switch for powering up or down anyway. 

Opinions have varied for decades.  As have theories of cathode stripping with the sudden rush of B+ voltage (though it hasn't ever been proven in lab tests).  But the hi-fi world wrote it off as bunk a half century ago.  It's mostly guitar amp techs (yet not designers) who persist in arguing for cathode stripping.

BTW, a 5Y3 or 5U4 rectifier tube will deliver voltage almost as fast as a SS rectifier.  It's the 5AR4/GZ34, 5R4 and 5V4 that have "slow ramp up."