The ammonium thiosulfate part - I think it is the B- not the red ferricycanide part, can sulfate out as a sulfur precipitate over time just like ordinary b&w fixer concentrate.
So I mix up my RA-RT blix 1l or 2L at a time. I have had the thio sulfur out, and resorted to mixing the replacement from bulk thio I had around, along with a few other mix from scratch ingredients, while I waited forthe replacenent order to come in.
Prior to RA-RT I used to mix from scratch the whole of RA-4 process chemistry.
Once I got a roller procesor I needed something that was more resistant to aerial oxidation, which RT most ddefinitly is.