Speaking as someone who has been at Google for about 10 years, I would caution against trying to paint "developers at Google" using broad strokes. Google is a multifaceted megacorporation housing a plethora software project categories. Through the years I've been deeply involved in a wide spectrum of them, ranging from "disconnect for 6 solid months and deliver a leapfrog for the masses" to "form an umbilical cord with a handful of enterprise customers." The techniques necessary to drive results in each case vary in accordance with the nature of the problem. This is where broad perspective and good judgement come into play, and dogmatic adherence to -- or dogmatic rejection of -- any particular development process presents a risk.