I love the Happy Planner sizes. I especially love the Mini, which is why everything is currently done with for the Mini. Also, I find it SUPER SUPER hard to find anything sized for the Mini in a format that doesn’t waste so much space (And I really, really dislike wasting page space when I’m printing anything)
Yes, you can size pretty much any insert to fit the Mini, by shrinking it to a certain percent, and printing carefully. However, when one can get two inserts to a page comfortably, it’s galling for me to have to do that. And since I don’t own any of the inserts I’d like, I have to make my own. And since I don’t own any of the inserts I like, I have to come up with my own style, and figure it out from there.