http://wccftech.com/a11-bionic-development-3-years-ago/

The serious firepower that the A11 Bionic brings to the battlefield can only be summarized as unchallenged. When the benchmarking scores are finally compared, we are certain that there is no chipset that will be able to hold a candle when comparing compute and graphical performance. However, in order to get to this point, Apple did not start with a 12-month period on their hands. The company’s journey started three years ago, during the time when it announced the iPhone 6 and iPhone 6 Plus, which featured an A8 SoC.

In an interview conducted by Mashable’s Lance Ulanoff with Apple’s Phil Schiller, the executive states that when Apple started to develop its own silicon, they always start with three years in mind, which clearly means that the competition is unable to catch up for a couple of generations: