If you have a dog or cat, your return grilles are pulling in hair every hour. Some of it lands on the filter. Most of what gets through wraps around the blower wheel and settles inside the duct runs.
Two things help. First, upgrade your filter to at least MERV 11 and change it every 60 days instead of 90. Second, schedule a duct cleaning every 2–3 years instead of every 5.