People changing them WAYyyyyy 2 early.
Tested in Beijing Air, Hepa filter exposed to an open window is reduced to roughly 50% effectiveness (filtration efficiency) after 1400 hours of run time.
That is roughly 2 months @ 24/7.
But this is with no pre-filter cleaning, or hitting the filter back from time to time with a leaf blower.
A filter should last 2-3 years if ran in the average 'Murikan bedroom 24/7, if general cleaning is in place.
One can make a case for Forest fire season, if you live next to the forest fire, but OTHER THAN THAT, Don't be wasting $30 on filters every 6 month, That's BS.
