In my school, canings tended to be two, three, or four strokes. I can’t recall hearing of anyone getting just one with the cane. In class, one with the slipper wasn’t unusual but two was far more common. Five was totally unheard of in both cases though, it seems to be absent from the English CP numbering system. I don’t know if five strokes of the tawse were given in Scotland.
I found the pain of each stroke did get worse. With the slipper, two was simply twice as bad as one because it tended to be one one each buttock. A third was worse because it tended to land on a previously slippered area and a fourth was about the same as a third. A fifth and sixth were even worse of course.