This is a very dangerous suggestion. Dan I am glad you have
had success with this, but I have found this the path to ruined
negatives. No matter how much time in this diluted fixer salts
and complexes of silver are retained in the film. My testing
has shown degraded negatives in a very short time.
To the OP you can fix diluted one night and refix in fresh full
strength in a few days and should be OK .
I think not dangerous at all. In fact a film fixed using a one-
shot fixer is much cleaner out of the fixer than a film from
a fixer which has been repeatedly used. There is another
margin of safety in that the fixer is Fresh, Unused.
I've dozens even scores of rolls of clean colorless negatives,
some from several years ago. The amount of concentrate,
or solid in the case of sodium thiosulfate, needed was
determined years ago via a series tests.
I suspect some wishing to use less than full strength fixer
confuse 'dilution' with the amount of concentrate needed
to Thoroughly fix the film. I made plain in my previous
post that the dilution will vary according to the amount
of concentrate needed and the solution volume.
I should mention that the amount of concentrate
suggested may not do for iodized film. Dan