I'd like to add that the best economy with fixer is obtained with a two bath procedure, in that way we may completely exhaust the fixer while ensuring a perfect job, as the second bath is fresh fixer. It takes the same time, we do the half in each bath, and when we dump the 1st bath we move the 2nd bath as first bath, that is still mostly fresh.
For an extremly good fixing we may even make a water rinse between 1st and 2nd bathes, in that way we don't carry silver rich fixer to the second bath.
Best of double bath is peace of mind, we always ensure a perfect job, with single bath we always have a doubt about how good is fixer, as exhaustion depends on how much halide the negatives had.
Probably first one has to do with fixing is exploring the two bath way, this has more economic impact that fixer price. Well, if ensuring a perfect job is cheaper

then why not?