Totally understandable. When I lived in a small place, I only had room for one box, so I got the biggest thing that would fit and scooped as often as possible.
That reminds me, some cats are picky about litter too, just like some humans will only wipe their ass with certain brands of toilet paper. So it’s good to find a brand they like and stick with it, but I know how hard it is to experiment when there’s only room for one box.