Question about Durable compressed gas cleaners

I suspect if you just held down the spray button you would fully exhaust the can in a matter of minutes, but this isn’t really how compressed air is used, at least not in my experience, i.e. you press the button for a few seconds and blast away dust from a PC intake fan, then move on to the next component. We managed to thoroughly clean the fans, radiators (water cooling systems) and motherboards of three systems with a single can.