Re: \"Have you contacted Clearance Delivery?\"
The fact is that there is a basic standard and then variations on a theme that suit that particular airport, its traffic and the manning in the tower.
For instance from many hours spent listening to BOS and JFK on-line I've noticed the following things:-
At BOS the alley's are controlled by Ground Control - you can start your engines, you get a clearance from CD, put don't even think about pushing back unless ground says so, then you call ground again for a taxi clearance.
At JFK, the tower don't wanna know what happens inside of the ramps, basically unless you need to push-back onto an active taxiway you can do what you like in the ramp area. You call CD for your clearance, and he tells you to call Ground for taxi. You call Ground for taxi, when you are ready to goto the runway. If it is evening rush-hour the guy or gal'll say "Hold short of Taxiway Alpha, Monitor Ground 21.65, wait for him to call you" So the usual 21.9 ground freq is now a flow control and paperwork finder for the Ground Controller - in the tower they must be passing a flight strip which the flow controller has marked with your taxiway location. After that it's pretty normal - but I'd strongly recommend a trip over to liveatc.net and listening to some different airports' feeds. Found out when that airport's rush-hour is, if it has one, and that'll show you why following the correct procedure is so important.
I've heard JFK on bad days, when the weather is at mins. there's snow everywhere, everyone wants to taxi to de-ice before going to the runway, and it ain't pretty - those frequencies frequently get overloaded. And half the country is on ground-stop or flow control. I think there was one day when it was so bad they stole a runway frequency for hold and shuffle control, as I recall one runway was a plane park!!!
There is a reason for procedures - they just mightn't make sense at the time!!