I just realized partially through the main quest... after a certain point. You're knee deep in dragons all the damn time... can't run from whiterun to winterhold without at least 4-5 of the angry geckos showing up.

Does it change after the mq or just stay swarmville

In my experience there a no more or less after finishing the main questline...

Sounds like I really need to reconsider doing the main quest till later. The shouts are nice, but the killing dragons all over gets old quick

I don't get Dragons that often. So far, I've had to hunt them down to unlock some Shouts.

Do the MQ whenever you're up to it. The Dragons still await you afterwards.

Pretty sure that's random, I only got attacked like 5 or 6 times throughout the entire main quest. Excluding direct-quest dragons like Dragon Rising, the first Blades quest, Alduin, etc.