So, about a week or so ago, I finally managed to get the majority of the animals in this game up to level 30, with Rex being the last one. The most recent 9 are still significantly below that, but I have enough snacks that I could pump them all up to 30 if I wanted to. I don’t, though! I’m still gaining enough friendship points, or XP, or whatever, each day that I don’t feel a big rush. I’m already at a pretty high level, and it’s not like gaining more levels actually does anything. I don’t exactly gain HP and attack bonuses.
Anyway, it took a long time to get to this point, and I really only managed it even THIS quickly by swapping out the animals in my campsite and cabin on a daily basis to make sure I was regularly gaining XP for the lowest-level animals. That way, they all hit level 30 within only a couple of weeks, and nobody sat at level 30 for weeks on end gaining worthless XP from requests.
I don’t have a point; there are no hints and tips I’m trying to give, and I don’t want to brag. It’s just that I did it, and I’m kind of happy about that.