Ladies who get their hair colored - how often do you touch up the roots?

My hair is a natural ash blond but I have a lot of gray, too. My hairdresser does a foil so she can do more in the gray areas and less in the back, so it blends well, not much demarkation. I need this done about every 8 weeks, but I like it to be fresh before social events, so sometimes it's only 5 weeks. My natural hair color is kind of a grayish blond anyway so in certain lighting it's hard to see the gray but bright sunshine much more obvious. My sister's hair is kind of Iike mine. She uses Root Rescue product between her appointments. Her hair looks great. I may try it.
 
I have highlighted blonde hair with very little gray, one side of my family doesn't seem to go gray, I actually wish I would get a few for texture. I have fine thin hair so I need the color to give my hair texture and, for lack of a better word, rough it up. I go 5 weeks, but could easily do 4 or even 7.
 
I have VERY dry, fizzy, difficult to manage and damage hair due to severals time of hair bleaching and dye. I touch up my roots almost every month without fail. I made it worst by doing rebonding (I have natural fizzy and wavy hair) and more hair dye.

The only remedy that fixed my disastrous hair situation was this Redken Cocktail Customised Treatment which i had did in the salon.
 
I go every 4 weeks if I want to keep them "hidden," but truth be told...my hair grows so quickly that I have no problem letting them go for up to 8 weeks. Otherwise, I'd been supporting the hair salon's monthly rent :smile:
 
I couldn't tell you exactly, but somewhere around 4-6 weeks... my hair grows quickly and sadly it's naturally very dark (vs my light auburn dye) so I just do it myself.

Naturally about a 2 and I dye to 7.43.