When you visually compare two hashes, how many digits do you check?

The strings hashed below are "retr0id_18b1f814a8e2d9c4fb9c" and "retr0id_1253dea672ebfa240e94", if you want to check for yourself.

@retr0id I used to just check the first 3 and last 3 hex digits but I've started to suspect that's a scheme that somebody's going to start to attack soon if not already

(Edit: oh, yeah, I see the image now)