"In the end I think what this illustrates is that writing a good, concise, clear, complete functional specification is not easy." A complete, unambiguous, and

"In the end I think what this illustrates is that writing a good, concise, clear, complete functional specification is not easy." A complete, unambiguous, and functional specification is called a program. May or may not be "good". The going back and forth that you describe as inefficient is where the collaborative creative act occurs, where you work with the person that needs a custom system to define what you can build for them.