Here is my timeline of system development (also rank-ordered for quality of system):
Take calendars. In the past, I did not have a calendar. I apologize to anyone who had to deal with me back then. I don’t know how I got where I wanted to be at the right time and place. I went through the hierarchy of systems, step-by-step. Right now I use Google calendar with a subcalendar for each of my different roles and responsibilities. Because it works, I spend more time using the system than working on the system.