Player rating for tournaments across all installments of Heroes.

No one is going to sum up days, experience, and skeletons, where did you see that? In fact, dimensionless units are summed up, which are ratios: days/days, skeletons/skeletons, experience/experience. You know perfectly well that the points for a map turn out to be the same even with a different number of days, and skeletons and experience are not taken into account at all (at least in Heroes of Might and Magic III).