One point that generated lots of thought for me was (from page 19):

Designers inevitably bring certain organizing principles to a problem at the outset. Even when severe problems are encountered, a considerable effort is made to make the initial idea work, rather than to stand back and adopt a fresh point of departure.

I can think of countless design projects, in both graphic design and IxD/UX, where I am presented with this fork. When you’ve been solving a problem, your mind has already assigned analogies, followed themes, organized thoughts, etc, and if the route you’ve decided on does not pan out, it is a difficult decision whether or not to scrap what you’re doing or to dig deeper (into what might be crap).

I feel that these “organizing principles” you, as a designer, bring to the the project are what make you a Designer. They give you brilliant moments of success and terrible moments of frustration. They are the reason you can be called a designer, as well as and occupational hazard that you must accept. These “forks” in the road, between continuing down one route or starting over completely, are necessary evils in the problem solving process- you have to choose one path because designer’s are not clairvoyant. We have no way of knowing, but we do have the ability to find answers to a problem.