Sony's twice-yearly upgrade cycle

Most OEMs release a new flagship device once a year, either in the spring (Samsung and HTC) or the fall (the Americans: Apple, Google, Motorola). Careful observers tend to know what to expect from these OEMs, within certain parameters.

Sony, however, maintains a twice-yearly upgrade cycle for its flagship model: the Xperia Z was released in the spring, the Z1 in the fall, and the Z2 in the spring again, with the Z3 (or whatever it'll be called) all but pre-announced for the fall by that strange interview with the director of Sony Mobile. Furthermore, Sony doesn't appear to follow any sort of recognizable tick-tock pattern. All three of the company's current flagships have looked identical, and yet each has fixed a major failing of the last (the camera and the display, respectively) - they've been "large tocks," I guess. The Z3 might represent a break from OmniBalance, meaning that it would be a "tick," but I'm not sure if we're to assume that means that Sony will release ticks in the fall and tocks in the spring or if this is all ad hoc.

So, a few questions:

1. Why does Sony maintain this idiosyncratic upgrade cycle when every other OEM has decided that once-yearly upgrades are the way to go? The Sony Mobile director's explanation from the interview, that Sony is iterating rapidly in order to keep pace with the competition, rings hollow to me: the Z2 seems more intended to fix a glaring flaw with the Z1 than to really keep up with a rapidly-evolving mobile space.

2. Why did the creative director of Sony Mobile give an interview basically telling people the fall upgrade would be more significant than the Z2?

3. Where does the Compact fit into this? The Z1 Compact is a spring release and has the specs of the preceding fall flagship. Will Sony maintain this pattern going forward? If so, that would seem to indicate that the fall flagship is their "tick."