I promote regularly scheduled maintenance of building systems to my clients. Homes and building structures (facilities) require check-ups just like our cars, trucks, and SUVs. Sometimes we procrastinate, get busy, or delay the service call. I have several examples of not following what I tell my clients to do. After 15 years, I finally had the trim on our house painted.
Earlier this year I remembered the air filter on the A/C unit was overdue for replacement. I installed a high efficiency filter system with 4” MERV 13 filters that recommends a filter change every 12 months (max.). Well I skipped my annual A/C check-up last spring, so the filter had been in the unit for 19 months.
Old and New 4" MERV 13 Filters
I cut a piece out of the old media to see how much dirt had accumulated between the folds.
Dirt in the deep fold of the filter media
The filter was definitely doing it's job. I expected to see more dirt, but we don't have an active home; no big pets and the kids are grown and out of the house. So I would not extend your filter replacement beyond the manufacturer's recommended schedule.
Just like your car; take care of your home by scheduling periodic maintenance. Like my Dad used to tell me; Do as I as say, not as I do.