The thing is, it takes a day or longer for the truss rod adjustment to set in. So you get it where you want it, but it is still settling in, and the next day it is different.
I'd say you should make very small adjustments only - no more than 90 degrees a day, and get it CLOSE to where you want it, allowing for a bit off settling over the next day or two. Wait AT LEAST 24 hours before making further adjustments. Shouldn't take more than a week to get it where you want it. Just remember, you're dealing with wood, an organic material. It's not like adjusting an EQ
Oh, and I just re-read your post - maybe you're doing everything fine, but after a truss rod adjustment you should expect the string height to need some adjustment the next day...