Shelter is SO overlooked as a priority.

A lot of my scenarios come down to the fact that you don't realise it is a survival sit until it's too late i.e.
Typically, lost hikers try to find a way out until it is dark.

And I always assume worst case - alone, injured, dark, weather bad. It which point sitting under a tree wrapped in a space blanket may be the best option to avoid hypothermia until I can see what is available to me in the daylight. Given the choice I would be whipping up a lean-to and a big fire - just have to plan for that not being an option.