I definitely have to come down firmly on the side of 'maybe.'
There are no rules to concert lighting, and you keep your job and get better jobs based on your ability to get the job done, keep people liking you, and not get anyone killed. Not in that order.
Being good at concert lighting means being able to adapt. There's no excuse for taking
safety risks, but beyond that, every option is on the table. You have a certain number of tasks to accomplish before the show starts - I make every effort to get my conventionals focused as quickly as I can, then
build position palletes for the movers, as these are the two activities most likely to annoy the band once they're sound checking. If I haven't finished these tasks... I have to get them done. I always go to someone working with the band (but not the band itself) and talk about it. I explain to the
road manager or
monitor engineer where I'm at, what I have to get done, and how long it's going to take. They almost always tell me to just do it. One in a while they'll ask me to leave the movers on the
deck, or the lekos on the
FOH Truss alone until the band's offstage so I don't make them shout. They want the show to look good too, so they're usually very understanding. And if the lead singer yells "What's with the flashing?" now the
road manager is the one who replies "They've got to get the lights focused! Just finish the
sound check!"
If you keep it safe, communicate to people what you're going to do, and then do whatever it takes to do your job, you're almost always covered. In the end, remember that you very rarely work "FOR" the band and they're going to lose more money than you are if they decide not to
play the event because the lights were being focused at
sound check. If I think there'll be a problem, I get the promoter or event
producer in the loop and explain the situation. I explain that "you've hired me to light the event, I want to do the best I can for you, and that requires me to do this and this... but the band was complaining about it. I don't think there's a problem now... but I just want you to know what was going on in case they mention it later. I did what I could to make sure they were happy, but in the end I had to do my job too..." Yeah, if the Rolling Stones say "Either the light guy goes or we do..." You're fired, but this practically never happens. Usually they don't care that much, and the promoter will come in on your side and tell them to do their job while you do yours. Protect the guy who signs your check and he'll protect you too.
Try to be as easy to get along with as you can and you usually won't have a problem. Keep it safe, keep people liking you, and keep producing quality results and you'll have way more good days than bad.
Art