Well because my computer has see through casing, i can see how much dust is collected in the dustcollector.

So when it's a little too much for my likings, i shut it down. Clean it all and run some updates if i want or need and start all up again. My computer has also the back vent blowing on full blast so it's not controlled. It's pulling air through the front blowing out of the back. That works also for keeping it pretty cool.
One tip i can give is don't put it on the floor. Putting your computer a little higher of the ground will result in less dust in the vents. Another thing and that is for the people who has air conditionened rooms, try to create over pressure. That way the dust in the room will be blown out because of the overpressure, keeping your computer a lot cleaner.