What is gained by learning Vipassana meditation in long retreats? My understanding of S.N. Goenka's method for learning Vipassana meditation is that the student is introduced to meditation in a 10 day retreat in which he or she sits in silent meditation for almost all his or her waking hours. This seems  a daunting way to introduce meditation to a newcomer. Also, for many people, it could be difficult to arrange for 10 days without family or work obligations. Thus, I ask: What does the student gain by through an introduction to meditation via a "marathon" retreat?
To put it succinctly you need to rub two pieces of wood long enough to get fire.

Likewise you need to meditate continuously for some stretch of time to see results.

As Goenka says "Continuity of practice is the secret of success".