I've been using a one-shot fixer technique with T-max films for some years now. Why? Because T-max exhausts fixing baths very quickly, so it was a question of economy more than anything else.(posted 8592 days ago)
I've found no drawbacks to using this method, apart from the extended fixing time, but diluted rapid fixer works in about the same time as a normal fix.
I did a few experiments with offcuts of 35mm, and the film takes about 4 minutes to clear, so I used the old 'double the clearing time' rule-of-thumb, and I give T-max 100 10 minutes in a one-shot fixer.
Dilution? Good question. It's got to be routine now, so I don't even think about it any more. I use 25ml of Ilford rapid fixer per film, and my single 35mm tank holds 225ml, and the double35mm/120 tank holds 450 ml, so that's an 8:1 dilution, right? (Hmm, I had it at the back of my mind that I'd been using 9:1. Ah well.)
The first films I did this way must be 6 or 7 years old now, and FWIW, they look identical to conventionally fixed ones.Some old research by Ilford, from their 'manual of photography', says that film emulsion swells more in low concentration solutions than in higher ones. This should mean that the dilute fixer is better able to penetrate the emulsion depth, but probably also means that washing time should be extended. I've never skimped on wash-time anyway, I just leave the film washing and wander off to get on with something else.
Good Luck with it Doremus! It does work.