You have absolutely no idea what you are talking about.
Where did you even hear about this specific number in how often they used to change their filters vs now? Do you have any idea what the reasons are for them changing filters, how they decide? What the minimum is? How they measure it?
You seem to not really even understand how air filtration works.
I'm guessing you've been smoking so long, you don't know what it's like to not live in polluted air. When you change an air filter, repaint a house, wash the inside of a car, you can immediately tell whether somebody is a smoker. It's fucking gross, and I suspect that it's not 1/5th, but probably 1/20th as often. "What makes me think that" is plain simple experience.
I don't have the full paper handy (and can't be bothered to look this up just for you) but the highlights should be enough for you on this one:
Where did you even hear about this specific number in how often they used to change their filters vs now? Do you have any idea what the reasons are for them changing filters, how they decide? What the minimum is? How they measure it?
You seem to not really even understand how air filtration works.