An extra 5-7 must be nice. The chin-up grip adjustment without the thumbs in the beginning? Not really sure what else you could be talking about. A couple of years ago i went from 0-ish to 2 ish range to about a little over a dozen-ish in a little under a years time for pull ups not chin-ups. Back then the gym had gone to one of those bars with the 3 grip positions not a flat bar.
Present day back in the 0 to 1-sh zone, dream bulker too ashamed to try zone other wise I’d give the monkey chin- up adjustment a go and report back. If they ever start 5k’s again my fatass get back up to 4-6 with a lot of embarrassment. Marines were all about chin-ups and pull-ups in a weird obsessive way no other branch required it.