The writings of Schon are a valuable and powerful set of observations that in their clarity of style and importance of message have changed the way modern schools educate their students.
Furthermore, it gives a tangible theory for improvement in design practice. Tacit and explicit knowledge, `world-making' and the definition of professional artistry are all idioms that we are aware of but do not have a label for in a design practitioner's context.
Schon defines what methods a professional must take to reach a level where skill becomes a habit and artistry results. Although the explicit detail is not elaborated on, in what happens in the reflective process, we do see how `artistry' comes about.
It must be said that reflection-on-action allows reflection-in-action to take place by the sedimentary, accumulated knowledge that comes through experience over time. This allows reflection-in-action by recalling and reformulating a problem, with a view on known past consequences. Experience leads to real intuition in the working environment.
This is the only flaw in an otherwise valuable work, its importance to a designer can not be underestimated.