I use fixer only as one-shot or withthe two-bath fixing routine
andhave ruined many negs by using fixer more than once.
I use 1-shot for negs, but I go through far more fixer for paper than film
I'd assume many of us do?
I'm loathe to waste money - even small amounts of money - I think it's not the money but the idea of "waste" (and the highly metaphorical act of pouring something "down the drain"
)
So for fixer and developer, I pour the trays into bottles after use, and top them off with butane. It's amazing how long dektol (Liquidol in my case) stays fresh. I start most printing sessions with tests on RC to experiment with dodging, contrast, etc. So when I set up, if I'm getting out used chemistry, I do a fixer test, which tells me if the fixer is good and if the developer is giving solid blacks. (I test my fixer all through a print session so I can fix as minimally as possible - TF-5, even late in the day, will clear paper in 20 seconds or so. Doubling that time beats fixing for 5 minutes
)
When I get out the fiber paper, I make fresh chemistry. But I often have sessions that are "all testing", as I'm wanting to learn more about registering and masking, duping film, etc. Package labels are pretty conservative - I imagine they want even sloppy workers to get decent results.