05ABC analysis: Why divide it into 3 parts?

It's called ABC analysis because it's divided into three parts, but I'm surprised that no one breaks this rule. Wouldn't it be fine to divide it into four or five parts depending on the purpose of the analysis? From practical experience, when conducting analysis in logistics system design, dividing it into 10 parts is too many, and dividing it into 5 parts makes it easier to allocate logistics equipment. In TCalc, ABC analysis is programmed as a 5-division analysis. Since this is no longer ABC analysis, we have decided to refer to ABC analysis 5-division as the conventional calculation in the software explanation. The division names are "A1" 50%, "A2" 20%, "B" 15%, "C" 10%, and "D" 5%, with the ratios being changeable as the default values. When allocating storage facilities, a 5-division system allows for greater flexibility in allocation. "A1" can be a PL automated warehouse, "A2" and "B" can be motorized shelves, and "C" and "D" can be PL fixed shelves. Alternatively, "A1" can be a PL automated warehouse, "A2" can be motorized shelves, and "B", "C" and "D" can be PL fixed shelves.