Well first of all Kazekage Gaara isn`t useless, maybe you just don`t have ninjas to make a viable team with him. Secondly, the chance of getting a rare from kage doesnt change when you draw one, you can get both super rares and still never get mei but enough dupes to make a kage 4*, its all rng.

You have the same chance of getting mei as gaara which is 1/8. However, usually after your 3rd-4th rare you might be getting rares you already have.

12.5%/1 out of 8 each time you get a rare.

Heck, I'm stilling missing Mei and Kazekage Gaara, Pulling 7 rares (Onoki, Darui, Chojuro, Mifune, Danzo, Killer Bee, and a dupe Onoki)

I still missing Darui and bee and im 60+ pulls away from 900+ pulls .

i feel like you, i'm at around 700 pulls and still no danzo and onoki.