How long can a battery possibly last

in the 90's m buddies nova had a die hard that lasted over 10 years
i like optima deep cycle marine batteries
the electrical wiring on the coast needed the grounds and connections either coated in dielectric grease or wire brrush scrubbed every two years due to corrosion which increased alternator current out put over time
i run the biggest battery i can fit in my road runner, seems to last extremely well-car has head lights, that's it