Color on top of color

I usually get my gray roots in a permanent color and then they mix shampoo with the rest of the permanent color and run through the rest of my hair only just to refresh the midshaft and ends. Is that too often for the rest of my hair ? I have this done every 5-6 weeks as needed but by then the midshafts are really faded and needs it. I dont have too much damage except for frizzies in humidity and it seems a little dry is all. I use a good conditioner every day.

When you have alot of gray in dark hair, its a pain.

Especially when you have to start doing your roots in permanent color and you have that heavy line down the middle of your head. Sometimes I feel like Im coloring too much, I hate it.

Thanks again !