Another factor is the maintenance on the system.

Dry chem fire extinguishers are supposed to be checked every 2 years, valve removed, powder uncaked, and recharged. Marine ABC systems should have the same maintenance interval.

A halon system, once the gas is spent, becomes ineffective unless you are in an airtight confined space. A marine dry chem ABC system has the best chance of working and buying the greatest time, but has a higher maintenance need.

I would say any system that is over 5 years without maintenance will be mostly ineffective.