It seams to me that there might be some confusion as to one-shot and re-use from what I can tell. To me one-shot is use it and down the drain. Re-use is do a session and pour it in a bottle for another day. I never pour mixed fixer in a bottle. I mix a batch and use it for that session watching my print or film quantities. Using the recommended numbers given by Ilford for their Rapid Fix. I normally wait until I have 10 or 15 rolls to develope before I start mixing new batches.
For film, I use a neutral pH rapid fixer that I mix fresh for each use. I use it once and dump it.
For fixing paper I use two fixing baths - both made fresh at the start of the printing session. I dump them at the end of the printing session.