I have had chronic migraines for the last few years since developing fibromyalgia. My T levels have been very stable the entire year that I've been on T. For the year, I've probably had the same number of flares that I've had in the past, but they're more focused around certain stimuli/conditions now as opposed to before when it was basically every other week or so.
Before, I'd just regularly be in pain and get migraines. Now, it's much more likely to happen when the weather is awful. Summer was the worst. Heat and humidity really screw with me. It doesn't get super cold/rainy here until February, and that was pretty bad too. I do take it as an improvement over years past though. Despite basically spending the whole summer on my couch, I've been relatively pain free.
Changing my diet, scheduling my sleep, and increasing my physical activity all helped a lot. I think that's largely why I've had a better year overall.