This is the central reason why I have studied, at length, how to expose and process age-fogged film, including the exact usage of benzotriazole in developer. I NEVER take a chance, but always do a clip test with any questionable roll. The results usually are truly superb but, again, one HAS to know the actual speed (clip test) and the necessary development time (clip test).
My rather recent lengthy post on how to employ C-41 film as B&W film I consider to be a gold mine of frugal insight on this matter: color film is usually cheaper than traditional B&W, and the chemicals used are the same as for B&W processing. Here, again: (there was a url link here which no longer exists)
It is not rocket science, but, still, scary and highly unusual for most to fathom doing. It necessitates taking the time with each roll, but it truly is worth it. To save precious inches of film I load in the dark, anchoring the film, with tape, to the take-up spool on the film advance lever. This dark loading also allows me to expose as many frames as I want to, without undue waste. It possibly is another example of how wacky I can be ... but my large repository of film, guaranteeing availablilty for a long time to come, posits otherwise. With this foresight, I am content. - David Lyga