Yes, there's not enough furniture that I love
yet that I'm not also using outside*, and I get attached to things easily and then have trouble changing them around because of my sentimentality, so I'd rather wait for the perfect idea. I have my main room and two other rooms mostly done (one of those rooms I want to eventually expand into the attic instead). The other three rooms (including attic/basement) I use for hoarding. I made a second character for a lot of reasons, especially including decorating their house, but I have NONE of their rooms decorated. I have a few bits of furniture arranged in their room and that's that (but the exterior is customised). HHA is always complaining it's empty |D But I can't decide on what to do with all the rooms.
*Like, I adore the mush and celestial furniture, but all that's outside, for example. But I've always had a mush room in my house, so I gotta come up with a new room! And all the stuff I loved from New Leaf is out, so I really have to dig deep, lmao.
I do spend a lot of time in Photopia/Harv's Island designing rooms, though.

There's a LOT you can do with the items already in the game and custom patterns/creativity. The other thing I spend a lot of time doing is downloading cute flat patterns from Twitter...
edit: It took me a while to get 5* because I didn't really like decorating outside initially (I found it strange to have so many items outside and messing with the natural aesthetic of the game). So I spent a lot of my efforts on finding things that I liked and that went together and then putting them outside so I could get enough furniture for a perfect town, which was an important goal to me. So that held me up as well.