The farther in the main quest you are, the more frequent they show up
Spoiler while dragons begin spawning as soon after you killed that first dragon they will be very rare, you can go for weeks without seeing one except on the dragonroosting /wordwalls
Dragons really start to appear more frequint AFTER you done the' blades in the dark' quest, first still rare but after a week or so you will see many more dragons appearing everywhere
Is this true?
I have looked trough some scripts in the CS, and as far as I can tell, dragons spawning is only based a few variables.
There is a variable that determines IF random dragons spawn. (We shall call this A, for now)
There is a variable that determines how many days apart they spawn. (We shall call this B, for now)
There is a variable that determines what the next day will be that a random dragon spawns. (We shall call this C, for now)
It also doesn't seem all that random. A is set to 1 after the Whiterun dragon quest. So random dragons will spawn from that point on.
B is set to 3, so every 3 days, a random dragon spawns. I believe this also means you will get attacked by a dragon every 3 days. It doesn't just spawn anywhere on the map as far as I know.
However, each time you encounter a dragon, a new C is calculates. This would be "current day + B".
But when you encounter a dragon in the mean time (so at a world wall or other fixed location) a new C is calculated.
(I have edited B to increase time between dragons, seems to work)
This would mean that if you visit a world wall (and thus a dragon) every 2 days, you would never encounter a random dragon. (Not tested)
To me, it seems the reason random dragons spawn so much when fast traveling, is because it seems more time passes when fast traveling.
I'm not sure, but less game-time seems to pass when you take your horse, instead of fast travel or a carriage.
This is just my thought.
It would be nice if someone could shed more light on this.
