Just seeking confirmation here: The sky is connected to all street areas in Arkham, yes? So flying monsters will not descend on locations. Is this correct?

Assuming it is, does anyone find that flying monsters swooping out of the sky to attack is a relatively rare occurrence?

Yes and yes.

Flying monsters moving so rarely in the base game is probably the reason why Gate Bursts add the seemingly unrelated automatic flying monster movement.

-Villain

The only location they can move to from the Sky is Devil's Reef.

Yeah well, I've always played it like this, but recently I started thinking about flying monster movement. Quite often for me it's been great to have flying monsters around as they'll move to the sky and then just sit there prevent the appearance of other monsters. Hey ho.