I use a rotary processor, I have only processed E-6 so far. I mix 140ml of final working solution (tank is a Jobo 1510) and use it to develop two rolls, in two batches one roll at a time, it's a two-shots use in fact.
I extract the concentrated chemicals from the original plastic flasks with a 10ml syringe with needle (the needle allows me to "fish" deep inside the flask) and I mix them directly in the Jobo plastic flask I use. I use a graduated cylinder only for bleach, but I rinse the cylinder with water which then goes in the bath.
I preserve the concentrated chemicals with propane/butane mix after use.
I expect the chemicals to last without problems for more than a couple years, I will have used it up before deterioration.
I think using a rotary processor kills many birds with one stone: quality, consistency of results, low cost (at least 70 rolls with 5l final solution, E-6 less than €1 per roll), no anxiety regarding preservation, no film leaders to test.
If one uses a Jobo 1520, and makes two rolls at a time with 250ml of chemicals each batch, 5l yield 80 rolls with this two-shots strategy. I do rinse with water between bleach and fix during the first batch in order not to contaminate the fixer.