Occam's razor (or Ockham's razor) is the principle that "entities must not be multiplied beyond necessity". The popular interpretation of this principle is that the simplest explanation is usually the correct one. It has inspired numerous expressions including "parsimony of postulates", the "principle of simplicity", the "KISS principle" (Keep It Simple, Stupid).
Though most of Occam's principles are enrooted in philosophy, many approaches (especially the principle of simplicity) can be found in the basics of design principles.
Given a choice between functionally equivalent designs, the simplest design should be selected. Implicit in Ockham’s razor is the idea that unnecessary elements decrease a design’s efficiency, and increase the probability of unanticipated consequences. [¹]
When comparing technologies that perform the same function, a technology that is simpler in design will tend to be simpler to construct and repair, but will tend to require greater skill to use, whereas a technology that requires less skill to use will tend to be more complex in design and more complex to construct and repair. For example, a straight razor is relatively simple in design and construction, but requires considerable skill to use, whereas an electric razor is relatively complex in design and construction but requires little skill to use. [²]
Now, go back and reread the two referenced passages, substituting design and technology with project management approach. I particularly like the straight razor analogy, mostly because I shave using a straight razor. I only had to cut myself once (badly) before I realized I needed real skills to use such a simple tool.
So, what's my transition? Just because you may know a lot about project management, doesn't mean you need to make things complicated. At the end of the day, very few customers care how it got done. They just care that the product or service was delivered on time and within budget. If you're looking to add project management control points, look for what will lower risk and increase value throughput. The idea is to make your process as simple as possible, allowing things to get done. Don't add control points to a process for no other reason than to make work for everyone. Don't simplify too much either, resulting in the wild wild west. I'm always looking for that happy medium. So, go forth. Study your craft and learn everything you can about project management. Just be careful not to cut yourself.