Some observations on our cat and how cat fur works, based on watching our cat regrow her fur after the vet had to shave most of her side and part of her leg: 

She’s a black kitty with random white hairs scattered around. Under that, her skin is dark grey and has white flecks, and each white fleck grows a white hair. 

For some reason, the white hairs grow faster than the rest, the black hairs are only two-thirds the length of the white ones.

Kitty flank hair grows faster than kitty foreleg hair. 

Cats don’t like the feeling of their tongue on bare skin either! She groomed very carefully on that patch while the fur was still missing, and is gradually getting less careful as the fur grows back.