Design strategies should always allot time for design documentation. Almost always, this is the least priority in any project, may it be Engineering design or software design.
Side Note: A project that I worked with did not consider documentation in their manpower allocation. After the engineering design was completed, all members of the engineering team were demobilized. Nobody was left behind to do the close-out of project documentation. The project is not able to collect multi-million dollar collectible for documentation. Worst, project close-out will never be completed without completing the project documentation.
One of the qualities of a good design is good documentation. An inventor may have invented a very good machine but if he is the only one who can operate it, then it's useless. It does not truly serve the purpose. The same is true in design. The assumptions, references, calculations, and all other data used one way or another in the design process to come up with the result should be well documented. This will be very useful in design verification. The verifier needs to have a very good grasp of the basis of design in order to understand fully the design itself.
If the design does not have documentation, it may be that even the designer himself may not understand what he has done after a few months. People are not computers where there is a way to extract contents from their memory or storage. Unless put down in writing, other people could not read what the designer is thinking.
I can still recall, being a newly hired Engineer in one of the companies that I worked with, I went to a review meeting. I was wondering how the other Engineer marks up the design drawings. There are so many markups that I believe should be referred to as a calculation, design basis, or specification. I then asked, what is your basis in commenting on the drawing. He answered back without any second thought. It is all in my mind. WHAT? I just said to myself.
Another example was when I was still working as a Service Manager with a company having an ongoing maintenance contract with a manufacturing company. I was told that the Electrical Engineer was rude and very strict on workmanship. I asked then, was there any plans, specifications, or documentation of the electrical works we have been doing for the company, I was told none. The electrical engineer was just pointing to where he wanted his cable ladders to be routed, lights to be installed and motors to be located. And if the result is not what he expected, then he will issue a rework. Much so, what is coming out of his mouth was rubbish. If only this engineer has a sense of responsibility for documenting what he wants even in a simple sketch, then other people will be able to understand.
These are examples where design documentation should have come in handy. In any design implementation, documentation should not be taken for granted may it be a small project or a very large one.