My record so far flying out was as told by the local tower controller:"
"PBP, taxi runway 29 via Alpha and hold short, expect a lengthy delay, I have 8 Diamonds in the circut, two Seminoles doing practice IFR approaches on runway 24, and two inbound IFR commercial flights for 29"
Needless to say I spent about about 15 minutes waiting for a slot big enough to do a rolling take-off on, and I was departing the zone!
If you're an IFR training flight and the airport is too busy, you just get to practice your holds
Long story short, any airport I've flown in/out of is more than happy to work with any sort of training flight provided the pilot/crew are on their toes and follow instructions to the letter.