It may appear that there is not much to understand, or that understanding doesn't matter, provided you know it. The first statement is true, and this is an advantage. We can (when we are young) climb stairs one at a time or two at a time. We tend to do the latter to save time. Counting in twos is faster than counting in ones - ten steps get us to 20 instead of 20. That is the most important thing to understand, and it applies to other tables - they enable us to get around faster, and, once we have learned them, to go straight to the top of the stairs. Zoom me up, Scottie! We can also jump straight back down again without breaking our neck, or stop anywhere inbetween, like a lift.
These things are not hard to understand, and are obvious once we've thought of them. Explaining things does not have to be conplicated, but it makes work meaningful rather than mindless.