Just last week I threw out some finally exhausted Unicolor C-41 chemicals I mixed up in late November. It was my first C-41 kit. stored the chemicals at room temperature between developments, and I added a brief wash step between dev and blix, thinking it would help keep the blix uncontaminated. I also did a bunch of chromogenic and expired-film experiments near the end of its run, when color fidelity wasn't as crucial, so I can't attest to color fidelity near the end. I figure I got about 14 good rolls out of it! When the kit went bad, it went bad suddenly, no slow degradation.
I'd like to try Rollei chemicals, but Freestyle is currently out of stock of those, and I don't know where to find Tetenal. So it's back to Unicolor for me. I think I'll try cold storing it next time between devs.