That’s the nature of the game. Things change all the time, and our scheduling department does an amazing job of accomodating it all. Owners can be…well… flakey, and they’d change their flight times 10 times a day if it suited them. Some people are chronically late, and some are almost always early. Sometimes a flight will pop up at the last minute and scheduling will do their best to make it work. When the aircell rings behind my head while enroute it’s almost never a good sign…especially when we’re on our way home! "we need you to fly out to Midway for a 4am show"
In my experience, most professional flight crews I’ve seen, whether charter, fractional, or corporate, who don’t have a dedicated dispatch department have been using www.fltplan.com or similar. You can file a bunch of flight plans all at once, but they are saved in queue and fltplan.com will only file them through duats on your behalf just before the scheduled departure time. I don’t think it clogs anything up at all if you have one on file and you never pick it up. Once you pick up the clearance though that initiates some ATC workload.
Notice: This may be obvious for our Canadian friends, but we recently discovered a little tidbit of information that can cause quite a hassle. If you file an inter-canadian flight plan, and never pick it up, the airspace is still blocked out for you. Example: You file a flight plan from Toronto to Quebec, but are delayed or cancelled by weather even before you leave your home base in the states, you have to call and remove the flight plan from the Canadian airspace system. Otherwise a few hours later you’ll get a call saying the C130 has just taken off to go look for you. Not good.
I’m not sure if I answered any of your questions…