Public policy needs research. Human history is absolutely stacked with "obvious" truths turning out to be harmful falsehoods.

For all we know, sugary carbs that tend to get stuck between teeth do their damage in minutes or a few hours and flossing at night won't help. Or flossing too soon removes enzymes in your saliva that protect teeth from buildup or disease.

Perhaps you can get a layer of magic plaque that protects the teeth. Who knows. Mine just get worse. They used to feel dirty without a brush. Now they feel horrible without a brush and floss. Sometimes I just wish for all my teeth to be ripped out.

But cavities are not the only problem you can have in your mouth.

Food particles left in the mouth for long periods can cause an inflammatory response in the gums. This can lead to bone loss in the jaw. And that can cause your cavity-free teeth to fall out.

Flossing through the space between tooth and gum can potentially remove such particles, which would help prevent gum disease. But it might not be necessary to do it every day. Once a week, maybe? After eating jerky or popcorn?

I have no idea how often it is necessary to floss to achieve a statistically significant reduction in any of the oral diseases, or how much of a difference there may be between flossing twice a day and flossing once a month.

My dentist recommends flossing whenever I brush. While the recommendation to floss is probably well supported, I suspect that the frequency may be more based on psychology than anything else. They just attach it to the brushing habit. Perhaps it would be better to attach it to "whenever you trim your fingernails", or "whenever you shave your legs", even though those are not related to oral hygiene.