Car use pattern will effect life of it. If it's used for short journeys to the shops it probably won't get to a fully charged state on the way there, before being drained a bit again when starting it for the journey back.
I had an irate phone call from my wife complaining the car wouldn't start one snowy winter, she'd gone to pick daughter up from a late school event. A couple of questions revealed she'd been waiting sat with lights, radio (needs ignition on) and interior light on for reading the paper...