Our main dust collector is a 20hp unit with a 36" impeller. You can hear the meter scream when it starts. Not really, but when you throw an amperage meter on it, it's pulling over 100 amps of 480 briefly.
There's four of us in the shop, the general rule is to take a quick poll by looking around and see if anyone else looks like they need it, or if they'll need it soon. There's no reason to shut it down if it's just going to be cranked up again I a few minutes. Some days it doesn't hardly get turned on, others it runs almost all day continuously.
The router has it's own 7.5hp cyclone. That kills me. There's no point in shutting it down between sheets, but it stinks leaving it on when unloading, cleaning the table and loading another sheet. It's doing what it needs to only half the time.