The old saying where I live is "If you don't like the weather wait ten minutes". A friend and I where hiking on a long day hike in the Cascade mountains one spring day when a fast moving storm overtook us. We where 8 miles in and had now way of returning in the storm. The storm hit fast it brought 70mph winds with hail. We would have probably died of exposure if we tried to hike back in the storm. There is no way in hell we could have constructed a debris hut. I have found that in a survival situation sometimes it is just not feasible to construct these shelters in time. The solution was to find a stand of low growing Silver Fir and Cedar Trees. Round up as much debris and line the base of the trees with the debris and climb in. This makes an excellent first need survival shelter. The storm passed as quickly as it came and we decided to hike out before dark. Both my friend and I where prepared for wet weather, but you add the wind and hail stones in and you have a dangerous combination.
On our way out it was already getting dark and we came across a unprepared family stripped down to their underwear shivering around a fire the father had made. Their clothes where all completely soaked. This fire did not seem to help them much because the wind was stripping away all the heat from the fire. We attempted to give some helpful information to the man about some simple survival techniques. He was not interested in listening, the classic I-know-what-I-am-doing syndrome. I always wonder to this day if the family made it out OK. My friend and I found shelter before we got soaked and hiked out toasty warm. We used very little energy to build our shelters and got in them quickly before the worst of the storm hit. Sometimes the simplest shelter can make a big difference. I think this type of shelter is often overlooked but they work well for me.