Do I still need to replace filter every 6 months if I only use ice dispencer occasionally?

use until water light shows that it needs to be replace NEVER rest water control unless you install new filter the filter will plug completely on will not let water pass

When the filter light comes on, I recommend a new filter. If your filter is clogged it may damage the pump inside the refrigerator and require a repair. The cost of the filter is far less than the repair.

The 6 months and gallon usage is an educated estimate. Actual filter replacement is dictated by actual usage which is why some people are able to exceed the 6 months. If you taste a change in the water or see that it is coming out the dispenser a lot slower then you should consider a replacement. I went 9 months on my last Lowes filter before I replaced it with a new one from lowes.