Well i disagree sort of.
Extreme survival would be being in an environment or eco system which you have no familiarity with. For example me being stuck in the middle of the kalahari or brazilian rainforest. Less extreme would be an environment i'm familiar for example Temperate and some forests further North...
Perhaps our definition of extreme is a bit different. My definition is, "any situation/scenario which is life threatening. While stationed in Nevada, I was very, very, very familiar with the desert environment (I lived there 5 years and hunted, fished, camped, hiked, and rode horses there) For several months I had a daily drive to my duty location on a 70 mile stretch of highway. Any breakdown along that highway could have left me stranded anywhere from a few hours to a few days. My familiarity would have only been helpful in making me aware of the importance of shade and water. Leaving the car to look for either would only have the effect of making rescue more difficult. However as I said earlier, in such a situation, having sufficient water would be more important; a knife large enough to dig with would be helpful in finding a cooler spot under the sagebrush but not essential.