When you ask anything on Photrio, you are bound to get conflicting responses
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I track usage. And I base re-use numbers on manufacturer's capacity recommendations, plus extra safety margins determined by my naturally conservative nature.
I have six matched (except as to colour) measuring graduates that have mouths big enough to pour directly into from the end of the tubes, plus three smaller graduates that are also matched (except as to colour), which are an appropriate size for a single portion of chemicals.
Three of the larger ones start out on the left side along with the small ones - one each for developer, stop bath and fixer. The other three large ones are on the right side. The ones I use for developer are the same colour, as are the ones I use for stop bath, as are the ones for fixer - you get the idea. In a perfect world, the colour scheme will work for the smaller ones as well - haven't managed that though.
For each print I fill the small graduates for each of the developer, stop bath and fixer with one portion of the chemicals. I then process the print and at the end of each stage I empty the tube into the appropriate and colour coded empty graduate at the other end.
When the larger graduates on the left hand side are empty, and the larger ones on the right hand side are now full, the measuring graduates are switched end to end.
Depending on your choice of chemicals, you may find that the capacity recommendations result in similar amounts of use for all three chemicals. In any event, I swap back and forth until I reach my capacity targets.
I use this for RC paper. If I was using fibre, I'd probably use a tray for a second fixer bath.
I use an indicator stop for this, which helps provide a backup check on potential over-use.