How often can I fly my own small plane? I was wondering about how often can one fly a privately owned plane? Is it somehow like owning a car where you just light up the ignition and just drive away? Obviously, there are a lot of regulations and rules... but say I have my plane parked in a hangar in a nearby airport. Can I just drive up to that airport and take my plane for a spin anytime I want (after coordinating with the control tower)?
Depending on what country you live in, yes, but it will cost you.

It's probably the cheapest to fly an airplane you own in the United States.  Here, the answer is yes, with very little restriction, you can just drive out to the airport and fly an aircraft within the National Airspace System.  You just must abide by the legal and medical requirements for you, and the legal and operational limitations of the aircraft.  Most airports throughout the country are uncontrolled, so you may have limited, if any, interactions with ATC.  The ability to fly pretty much anywhere you like with very few restrictions is what makes GA so appealing in the United States.