I doubt that Steve Jobs, Jeff Bezos, Bill Gates, Mark Zuckerberg, Sergey Brin and Larry Page (to name but a few) ever thought about their “productivity system”.
And I’m pretty sure Bach (to name someone from a different industry 
) didn’t even have a “productivity system”. He just composed using pen/pencil and paper. And not without success.
He was also quite lucky there weren’t any podcasts yet to discuss which fountain pen he should use.
Point taken, but almost all of those people go or went to eccentric lengths and expense to organize their lives.
Bach just used the old simple trick of having so many kids that you can’t stop working.
Actually some of them, I know for certain with Bill Gates use Time Blocking, which would nessessitate some form of task list.
Craftsmen the world over are continually refining their processes and opining over the tools and trends of their time.
Quite to the contrary.
Doesn’t mean he didn’t have a system. And I can’t think of a composer whose music sounds more systematic.
Now that made me laugh!! 