For corporate operators at Teterboro N.J. (KTEB), the primary corporate airport for New York City, it is very common to have aircraft sitting on the taxiways and ramps with engines shut down.
Having delays of over an hour is not uncommon at all. It all starts when you call for your ATC clearance, which can take up to three or four calls before clearance delivery answers. Then when they finally answer you they will tell you to call back at a certain time. Then at the appropriate time you may or may not receive your clearance, which is usually not the flight plan you filed. Then you are directed to call Flow Control to be issued an engine start time. Then the real fun begins.
You start your engines and call ground to taxi, ground calls back and tells you to contact clearance delivery again. You call clearance and they give you an entire reroute and tell you to recontact Flow Control for a new engine start time. There is no reason to tell them that you have already started engines at the last start time, they don't care. So, you call Flow Control and if you're lucky, really lucky they will tell you to start engines now and call ground. Usually, however, you will be given a start time from anywhere from 30 minutes to an hour away. If it is the latter you shut the engines down, the first time for this departure.
Okay, the second start time comes up, but this time you don't start the engines, you just call ground for taxi instructions. Of course when you try and outsmart the system you get caught, ground calls right back and says to follow the aircraft that is coming up the taxiway behind you to the active runway. Oops. Now you're in a mad rush to get the minimum number of engines started to taxi as fast as you can. As you are madly rushing to get the engine/s started you hear ground tell somebody else to follow you. As this would be very difficult for the other aircraft to follow you because you are still sitting on the ramp this will sometimes irritate ground control, well actually all the time. Now you must come up with something very clever to explain why you are not ready to taxi, like the coffee is not hot, the chocks were not removed, a passenger had to run back inside to get their briefcase, etc. However, no matter how creative you are, at this point you are usually screwed. The dreaded words of, "Cancel taxi instructions and contact Flow Control" is heard. Yeah, you're screwed.
However, lets us say that you do get the engines started in time and you taxi out to the holding point. As the holding point comes into view you start counting the number of aircraft sitting in the holding area. On a day as the one I'm relating there will usually be about 10 aircraft there. Now what occurs is what I call the holding area/point dance. As you join the back of the line you get as close to the grass as you can and then turn as tight as you can toward the taxiway, the first aircraft in line departs, then everyone in line turns back toward the grass, then back to toward the taxiway. This is repeated until you are number one. If you have my usual luck this is when the tower announces that New York TRACON has shut down all departures. How long you ask, they reply they really don't know, so you tell them that you shutting down your engines, tower tells that is fine and that they well call in time for you to start your engines. So you shut down your engines for the second or third time.
Now of course if you don't care about cost, or you have excess fuel you can leave the engines running all the time. However, I have heard more than on one occasion of people having to go back to the ramp for more fuel, so be careful.
In case you have not figured it out yet, I hate going to Teterboro.