I am religious about using the Standby.
Same here. Especially my hands when playing.I am religious about using the Standby. On breaks when gigging I would put it on Standby.
Just like exercise and the human body, a warm up and cool down is important before going
full monty!
Also use it on breaks at gigs, etc.
How about when you're just hanging around your place - you play a bit and then remember something you needed to do that'll take 5-10 minutes.
Standby on or off?
That's fine too. I think it's just convenient to flick the switch on the amp.^^^ I'm pretty sure I just read somewhere, from a builder, in 2023, that standby switches are completely unnecessary for "taking breaks".
The gist was: warm it up, play, and just turn your guitar volume down or use your tuner mute when you aren't playing.
I follow the Mesa manuals, which say to use Standby for at least 30 seconds at startup. Then I put it on before turning the amp off. Also use it on breaks at gigs, etc.