Fairly simple. In the first scenari

Fairly simple. In the first scenario, you are flipping it in a fashion such that the phone has very little surface area for air resistance as relative to the force vector that is causing it to spin. In the second, you are flipping it very close to its center of mass. However, in the third, you are flipping it with a wide surface area for air resistance, and from a point that is as far from the center of mass as possible. This gives you a very wide margin for human error, which in the end I believe this comes down to. Even an "almost perfect" flip isn't actually perfect. There's just too large of a margin for error for most people to make a perfect flip.