Great insight in to problem solving. One thing I'm curious about is how environment plays a role whether in a high or low stress work place or social environment, etc.
My response to this is that environment is a little like what the author describes as mood. Different environments help frame problems in different ways.
A high pressure environment might drive aggressive simplification, skipping steps and question assumptions in order to side-step entire issues. It might also accelerate the time taken to exhaust solutions and put the issue to one side for background incubation.
A more relaxed environment might foster more creativity, more connection making and a more playful approach bending and transforming concepts and risking absurdity.
IMHO if you are really stuck on a problem then changing environments is one of the tools to try to help unstick it.