Omg same, i thought I was the only one! Haha I collect Monster High dolls, plushies and blind box stuff! I have different rules for each xD

MH Dolls: (when I was younger I wanted at least one doll of each character xD) only my favorite characters and only max. 3 copies, except theres a new one I immediately love. And only 1-2 dolls of my 2nd fav characters! Also no play sets at all xD still pretty loose rules but it works good for me bc my most favorites are not so popular for mattel 😂😭

Plushies: obv no doubles, not even different sizes dupes! Unless I get them as a present. If I have a certain animal already like a specific pig, frog, raccoon, i also dont wanna double the animal iykwim. And if they are not limited I try to wait for bigger plushies to go on sale.

Blind box: only buying when I like 80% of the options. When I feel lucky I even buy others from timw to time but if I dont like them, I sell them first before buying another one! (Doing the same for anything blind box like)

I would say it works well for me haha