There is supposed to be a 16 day repeat cycle to the data granules, but lat-longs at day 1, day 9, day 17, don match up. Why?
A. There is a 16 day repeat cycle, however you cannot expect that granules separated by 16 days will exactly align. The orbit slowly changes, requiring periodic orbital maintenance burns. It is important that you make use of the lat/lon data that are included in each granule to find the closest FOV match or to interpolate data in one granule to the position in the other.