How long do pump filter cartridges last?

Cartridge life varies widely. Reviewers and manufacturer pages cite roughly 200 gallons for the Katadyn Hiker line, around 1,000 liters for hollow-fiber elements, and up to ~50,000 liters for the ceramic element in the Katadyn Pocket. Murky water shortens all of these dramatically; specialist subreddit threads repeatedly warn about clogging mid-trip.