How is it considered “common” when no one anywhere has ever done it this way? If I had been paid by the hour for all of the tables of rote math I performed in grade school, year after year I would be rich. We did tables until I could recite any calculation of addition, subtraction, multiplication or division in seconds - and for years ever after you could wake me from a sound slumber and ask me any basic math question and I’d blurt out the answer - still within seconds. The function of doing math at the basic level is not important enough to do it using this kind of method. The value of rote memorization is that you retrieve the answer from the old memory bank. The value of muddled cross-skipping is? What? Anybody know?
Whatever method is used, has to give the student the ability to look at an arithmetic problem and know right and wrong...if they are doing calculation on a machine. Machines can replace our drudge work calculations, after they have become drudge work, not before.
My parents would not allow any of us children to go in the water on an inner tube before we were competent swimmers. Relying on calculators or computers, is the same just different context of getting out of your depth.
DK