The big problem with home darkrooms is usually the lack of processing quantity. Not many shoot and develop 5 or 10 rolls each week. So it's difficult to be economical by buying larger quantities of developer. Once you open the concentrates the clock starts ticking.

I remember that the hobby kits have instructions on how to reuse the developer to process more rolls in the same soup. Usually by extending the process time for each subsequent roll or batch. That way you could process 20 rolls from a liter of developer, using it 4 times.

In my early days I would do that, process one roll at a time and reuse the developer 3 times with slightly extended process times for each additional roll to compensate for the depletion of the developer. Even when using the developer up in the same day (4 batches), I saw differences in the subsequent batches. The effects of reusing are particularly noticeable in the edge markings, and are harder to detect in the image area, until you print.

You do have to make sure the roll is totally covered in solution, or you'll get processing marks in the image area, and don't neglect the effects from sprocket hole surging in scant solutions.