I agree completely with the point about reducing lesser goals. We tend to fragment our mental ressources and accomplish less.
But how can one be in flow "at all times" as the title of the article suggests? It's impossible unless you're a Budddhist monk or you're always tripping on psychedelics.
In my opinion, it's very healthy to allow for moments where your mind can wander. It also boosts creativity.
Maybe that ONE OUTCOME you're looking for won't make you happy. You'll discover that if you let a healthy amount of doubts and thoughts distract you once in a while.