I have a small two bedroom apartment on the fourth floor we used as an english acadeny. Right now irs a kids play area and office for me. I could get 100 bikes in there but I find the four that I ride do what I need. Unless I have a specific purpose I don't plan on adding more.
Improving or replacing what I have, but I can only ride one at a time. My kid yas an awsone little custom folding bmx/folder/mtb. I Have a bike ready for my youngest, and my wife has two that she never rides.