So to kick off this discussion, I guess I should say that we currently live in an apartment with two bathrooms, so I've commandeered the shower stall in one of them to use as the wet side, and the dry side is just outside the bathroom in a room we use as a study, so it's a semi-permanent darkroom. I can close the bathroom door during the day time to load and process film. I have black curtains to reduce the light level significantly in the study area, but it's not dark enough to print during the day, so I need to make another shade to improve that situation, but meanwhile I can print at night.
Our previous two apartments had only one bathroom, so the darkroom had to be completely mobile.
We were only in our last apartment for a year, so there wasn't much time to really get things going, but I did find a couple of ways of speeding things up--
Monobath processing. It took a while to dial in the formula, and the monobath really has to be tailored to the film, but once you've done the testing, you really can get good results this way, and it doesn't take up much space. Here's the long thread where I was posting my tests and results--
Another thing that I did was to keep a tank line for film processing in a large covered plastic storage bin. I could just slide it into a closet, pull it out and put the tanks in the bathtub for film processing without having to mix chemicals or even measure solutions every time.
My previous dark/bathroom was in a place where we lived for four years--
--so with practice I found ways to speed things up, like pouring working solutions that were still good back into bottles for that purpose, so I would have them ready for the next day's session. I had the enlarger on a rolling typewriter table that could fit over the commode with my dodging tools and focus sheets in a folder that fit under the baseboard. We had a storage closet, where I set up shelves to hold the darkroom equipment and solutions. The enlarger rolled into the bedroom/study, where I'd also built a loft for the bed to maximize space.
Albumen and other kinds of UV-based printing don't require total darkness, so even though these processes are labor intensive in some respects, they can make use of time when there isn't time to set up the full darkroom. Much of the time in albumen printing is taken up by exposure (my best negs take about a one hour exposure in indirect sunlight, 20 minutes in direct sunlight), so you can even do other things while printing.