It's not entirely an IP issue only. I use VPN for my accounts and for commenting, if your acc has a bit of age already and you have posts and comments with upvotes and mimic normal user behavior then I get no commenting limits.
If you make a new account then after creation do absolutely nothing with it (I suggest antidetect browser because it keeps cookies/loged you in). Then 24h later make 1 comment to a sub that allows 1 karma accs to comment and give random comments 2-3 upvotes. Then do nothing with the acc again for 24h, then log in and comment again - be smart, reply to top comment and write some agreeable shit that gets upvoted.
If you get 10 comment karma then you are pretty good to comment in most subs but if you comment with an inactive acc again fast then you get the limit.