I would point out, however, that I do re-use film fix (Ilford Hypam currently). I keep careful track of how many rolls I have fixed - my capacity target is about 2/3 of the manufacturer's recommendation. I monitor clearing time. I also watch out for any sediment or build up of "crud" - if any appears I stop re-using that batch.
Unlike some others, I also use HCA with film.
In short, I fix films in re-used film fix but, IMHO, I am careful and conservative about how I do so, and have the knowledge and experience that permits me to do it safely.