Finding an optimal process may not be easy. For example, I analyzed causes for my sub-optimal sleep and work patterns. I discovered that the problem was my preference for working until late at night and sleeping during the morning when much business is done. Flexibility is the key to an effective personal quality system. Humans aren't machines, and their processes shouldn't be totally programmed.
Personal productivity depends a lot upon psychological mood.
And some variability is necessary in all types of creative work. When in a creative mood, rather than stick to a fixed plan, it may be more effective to deviate from the plan. I've also realized that my system should have an ever-evolving structure. Results of quality analysis should be documented in some way. Drawing a flowchart is often useless when analyzing a personal process.