It depends how you define "flaky." I think of a flaky person as someone who keeps changing his mind -- and as someone who will miss appointments with you. Someone who will just fail to show up wherever he's supposed to be. In other words, he'll "flake out on you."
I've lived in NYC for 15 years, and in my experience, New Yorkers are (in general) the opposite of that. They are rushed, busy people who highly value their time. They schedule things and keep to those schedules. If something comes up, they inform everyone "I won't be able to make it at 3pm. Can we change it to 5pm?"
If you want to schedule a get-together, it can certainty take a long time to find a time that's good for everyone. People tend to have things booked weeks or months in advance, and they have to slot you in.
But I wouldn't call that "flaky,"