The way I understand it is the TOTAL number of points for all room types throughout the year can never change (unless they add on more rooms to the physical building). How that total is allocated can change from year to year but is cannot vary in any one year by more than 15% (I think).
What has happened over the last few years is an effort to reduce the # points for Fridays and Saturdays and increasing the points for Sun - Thurs. Most of the weekly totals have not varied much.
It has been suggested in other threads that the total change desired by
DVC varied by more than 15% therefore had to take place over two years.
Hope this makes sense.