Contrast and phase detection are 2 separate things, one cover roughly 40% of the screw with 399 point the other cover most of the sensor with 25 zones.. The emphasis thing, the camera is trying to be smart and check if the focus is locked or close enough it will shoot, if it's completely off it will not, I shoot like you always in continuous so I don't even bother to check other options, I always use af priority, if you need the moment and u feel luck I would try shutter priority, but never the emphasis thing since is unpredictable... One more thing that I did also is to map my centre button with hold focus so I can still use the old focus and recompose method of the continuous wide doe at give me what I want... I hope someday Sony will give us the ability to map an entire focus mode in 1 button that include mode and zone, so I will be able to switch between af-c wide to af-s point with 1 switch button.. But I know this will never happen they still have to figure out that their 35 1.4 is full of bugs for what the aperture ring concern