Studio time is studio time, not rehearsal time.
This is a soundcheck, not a rehearsal.
I do this for a living.
If you can sit down, do it. If you can lie down, do it. And if you can catch some kip, go for it.
They're all from work - the first two boil down to getting your shit together and preparing in advance whilst not taking the piss out of others by thinking you are so important, you don't need to know what you are doing.
The second is largely for when a Man very helpfully tells me (usually incorrectly) how to do something. Particular highlights include patiently explaining to me how to coil cables and that I need to make it louder with 'that big slidy thing' when it's at the legal/licensed limit, it's actually the Number 3 sub that I've sent the signal to/and it would the big fader you're referring to and it's not my fucking problem that you are deaf. However, it also applies when feeling a bit out of my depth - I get paid for this, so I can do it.
The third is pure common sense for long days, hefting gear and not knowing when you'll next get a chance to rest, eat, shit or just not run around like a blue arsed fly in the pissing rain trying to make sure that the lead singer somebody important doesn't end up dead from electrocution.
The final one is from too long spent crammed into a van with a bunch of twats en route to yet another gig or festival, especially when one is being particularly irritating/rows are brewing.
'Fuck Off Filters at the ready'. A Fuck Off Filter consists of hat, hoodie pulled up, headphones on and sunglasses firmly attached to the face. NOBODY speaks to anyone with a Fuck Off Filter engaged and it's advisable to have it ready at all times just in case somebody pisses you off.