I routinely leave exposed B&W roll film for weeks, occasionally months. I've processed film (Verichrome Pan and Plus-X, as well as B&W processing of Kodacolor) that had been left for up to 20 years after exposure. Start getting into multiple years, and things get iffy (multiple decades sometimes works, though).
The big problem is a) when you need more holders and forget those were loaded and exposed, as opposed to empty and left in "exposed" condition, or b) when you sell off a bunch of "old, disused film holders" with your exposed film still in it...