I wear my hair so short that I could never get 6" of roots. When I get my hair cut it is less than 1" all over my head. When I did color my hair 20 years ago, a single hair cut would automatically take me back to my original color.
I have considerably more gray now at 64, but I earned every one of them and had lots of fun.
I have worn my hair this short for 30 years and like that it is wash and go.