Epistemic status: More of a heuristic than an iron-clad law. Hopefully useful for decision-making, even if it's not a full gears-level model.
Related: https://www.lesswrong.com/posts/vHSrtmr3EBohcw6t8/norms-of-membership-for-voluntary-groups
In software engineering, there is a famous dictum which Wikipedia knows as the Project Management Triangle, which takes the following form:
Good, fast, cheap. Choose two.
The essence of the triangle is to point out that while good, fast, and cheap are all potentially desirable traits for a project, you cannot usually (or ever) get all of them at once. If you want something good and fast, it will not be cheap; if you want something fast and cheap, it will not be good.
I have observed that a similar triangle seems to... (read 1372 more words →)
N=1, but I didn't floss regularly for years, but I found that after I did so it made an enormous difference in my bad breath, to the point of eliminating it entirely for most purposes. Obvious conclusion is that my breath problems were the result of bacterial buildup between my teeth that wasn't getting removed by normal brushing.
I suspect that a lot of tooth-brushing advice is like this: maybe not rigorously studied, but nonetheless upheld by anecdote and obvious physical models of the world.