Dividing one's mouth for teeth-cleaning

[mtbc]

We are commonly told to spend a half-minute on brushing the teeth of each quarter of our mouth. I imagine that this idea entails having one central incisor in each quarter. Do people really divide their mouth into these even quarters for cleaning their teeth? Personally I divide mine into twenty unequal regions (2 × 2 + 2 × 4 × 2):

Central (incisors and canines),

• upper jaw, lower jaw (2)


• faces: front, back (2)

Side (premolars and molars),

• upper jaw, lower jaw (2)


• faces: front, back, top, far-end (4)


• left, right (2)

I wonder how others do it. In interviewing my children I found that they too have their own systems that do not comfortably divide into these mouth-quarters.