Oh does this only apply to actual furniture, not items like saplings, unidentified fossils, etc? I haven't tried it for my house, but I've filled up the entire museum room with just saplings and it has never told me that it's too full. If it does apply to furniture, that bums me out because I plan on eventually furnishing the museum exhibits and make like a japanese style room but I already have so many furniture items in mind u_u