Once every two days is far too little to remove accumulated bacterial growth unless you eat a diet that has very, very little easily accessible carbohydrate.

If you want to see this in action, you should try getting yourself colonized by some chromogenic bacteria. These helpful little critters make black stains on your teeth that don’t easily brush away.

If you brush 2–3x per day, your teeth aren’t blackened, even with a normal Western diet. But even 1x/day and you start to see stains; less and the staining is more pronounced.