Since I didn\'t do a good job writing the last question, and most of the answers were good, but not at all in the direction I intended for the question to go in, I deleted i
Referring the page you linked to - I say follow the processes. I am a solo dev and I follow these processes. You can't write software without knowing your requirements and pre-requisistes. As others have said, get to know how you work and your strengths & weaknesses. Also, sometimes you'll get stuck & get for a little outside help. Nobody knows everything.
The whole process takes time (often never ends) and I have killed far too many brain cells over the years to store every detail in my head. Mind maps, flow charts and things like OneNote are good for non-coding long-term memory. Try to keep the bulk of it in one place or at least linked together so you don't have to try to remember where to look for it.