One side of the disc has been divided into 30 and the other into 31 compartments. This suggests that the moon is not the subject. Because then we would expect 29 and 30.

Possibly the structure with 29 + 30 = 59 (which as - I believe - also was in the minds of those who created Pachamama) has been adjusted to fit the sun by increasing with one unit in both terms to get 30 + 31 = 61. Structures live longer than their contents.

If we count 6 * 61 we reach 366, i.e. just one day too many to reach the yearly period of the sun (which also of course has other periods - like the day).

But there are ways to avoid this minor problem.