I'm one more degree of anal on this. I mix my c-41 chems from the raw chemistry, and will do as long as I can still get the components.
Usually I work on saving up at least 8 rolls of 35mm or 120 before I mix. I used to try to reuse twice for the peak results. Then I pondered replenishment

I am experimenting on a replenisher, and have been able to stretch this stuff out for 4 months if I am processing every few weeks, but have not done denistometer testing to see how building iodide and bromide levels may be impacting things as time and replenishment goes on. Eyeball density stays good, and the print colours look ok though.