Well, right now we have two seats installed, one that lives in my brother's apartment in a corner of the living room when it's not in his car, and a base in our living room. The bucket and its two bases I was planning on selling when DD is out of it, because we have NO storage in our condo. We do plan to have another but not in this condo, and we won't be moving in the next year either.
DH really surprised me, though. I said something offhand about selling the seat, and he said no, it will go in the storage area under the staircase because we are planning on having a number two. This coming from the guy who originally only wanted one, and IF there was a #2, he wanted 5 years apart. Hmmm. Plus he has been talking a lot lately how much he misses DD being in my belly and feeling her kick etc.
For the most part, we avoid the issue. I'm not a carseat collector. We will buy one more seat (RN XT) before DD outgrows the bucket, but after that probably the next seat we buy will be a booster or combination seat for DD's friends at school age. That seat will most likely stay installed, unless it needs to come out for adult riders, in which case it will probably go in the trunk or living room as it would only be a temporary thing.