I should probably replace it water filter in my fridge because it's been more than 2 years since it's been changed. The main reason being, it now only filters water for the ice maker, as water no longer flows through the door dispenser. Over the period of a couple of years the flow slowly decrease until it got so slow, it would "time out" and stop before a glass was would fill half way (I gave up trying at that point), now the dispenser won't even drip. I assume the supply line very slowly got so cold it froze, but who knows.
On my fridge (a Samsung french door) the "replace filter" light comes on every 6 months regardless of how much the water is being used. I replaced it the first time at 6 months, then once a year after that because it was such a waste.
I just looked up the filter for my fridge and they're $23 for 2 on Amazon. Boy it's a good thing I don't have the newer version of this fridge as the filters are now $50 EACH!