Well ORIGINALLY Apple's OS schedule wasn't so rigid when we established our cycle. However in the past few years they've become very reliable. This whole schedule was explained to me by accounting here, when I asked something similar; Apparently it boils down to how our release rolls out globally. For instance, we want to release in the US just before the fourth quarter (When companies are going to be spending their budgets as fast as possible), a few other financial events in between but the