All joking aside, I do think it’s wise to have an empty coop at hand for emergencies, if need be. I used to have a smaller second coop that was great for using it in situations such as a broody mother with her chicks or a sick chicken. I had to tear it down when the section of land it was on started to get seasonal flooding. The upkeep wasn’t worth the price/labor. I do miss having it though! It came in handy several times. It’s just difficult to not letting those extra spaces get filled with permanent residents!
I am hoping to build a second large coop but I am weighing pros and cons, financing. When I only had 7 chickens in a large coop/barn, it was very easy to keep clean and because the coop was new, maintenance was simple. Years later, more chickens added meant more frequent cleaning (picture someone making a face of exhaustion here), more amount of bedding ($cha-ching$) and with age (10 years now) come issues like rat infestations, patching holes, roof leaks, wood rot, painting. So more coops COULD mean more work, more money..if not for the few years after it is built, then later.
Really, I think it comes down to maintenance and financing and how much more time and effort you’re willing to put into cleaning. Some people build really inexpensive coops that work for their needs too...ones they don’t mind tearing down when the maintenance issues arise. Lots of options out there. It all depends on what is right and works for you.