Firstly, apologies it seems that so many people on this forum fly Airbus that I forgot to even mention that.
Secondly, sure my company has specific escape routes when we fly over mountainous terrain. I am talking generally about non mountainous terrain.
I actually did some calculations and here is what I worked out. The closest any two airways are spaced in almost any part of the world is 10NM from centre line to centre line (am I right here? Or is it 20?). At a ground speed of approximately 500kts if one were to turn 45 degrees left or right one would have to cover approximately 14 NM in a straight line before intersecting the next airway and this works out to around 1 minute and 40 seconds. So if you were to descend at 6000fpm you would lose approximately 10000ft. The emergency descent would take no more than 5 seconds to initiate so that leaves you with 1 minute and 35 seconds to judge distances and decide where to navigate.