I had a real darkroom (no running water, but still not a bad arrangement) when I was in high school, and we lived in a suburban house with lots of space and a spare room. Haven't been able to do that since then, but when I saw what some people were able to do in Eastern Europe in tiny apartments during the last years of Communism, I realized that it was possible to set up a darkroom anywhere, if you had the will to do it. An even more extreme case is that of North Vietnamese war photographers, who might be issued one roll of 35mm film to be used over a period of months and developed in a teacup at night in a tent.
The more you use it, the easier the setup and breakdown get. You find little ways of making it more efficient. I can usually be ready to work in about 15-20 minutes, depending on what I have to do.
Eventually, though, we'll have more space, and I'll build a proper darkroom.