Thanks for your help, Sandy.
The slowest speed of my processor is 26rpm; my film is TMY 8x10. I can do all my development in one step, except for N+2, which works best if I split it.
Regarding your last statement ("This assumes that the 400 ml will be enough to provide complete coverage of all of the films being developed.") - how much would that be per 8x10 sheet (using 2:2:100)?