I think this "flow" or "zone" phenomenon definitely exists, and I think there are 2 different ways to "access" it.
One is highly labor intensive it basically consists of hyper focusing on the table and clearing your mind of all other thoughts (almost like meditation, but more concrete than that) so that you only see, smell, hear, and feel poker poker poker...almost like in the movie "the matrix" when Neo slows his perception way down so he can "dodge bullets" ha ha I'm being overly dramatic but you get it.
This first method is very intentional and basically consists of picking up micro patterns and micro tells
and tapping into a "rhythm". But when you're in that zone you frequently find yourself making amazing calls when you are barely ahead and making amazing folds when you are barely behind and to YOU it doesn't seem hard at all; it just seems obvious...but to the other players at the table you appear to have poker super powers.
The second way to access this "flow" or "being in the zone" is almost the opposite of the first way. It is basically accessed by completely letting go of the logical and analytical side of your brain and letting your intuition take over. I believe this is what we are seeing when we see a brand new player go on a tear or a "beginner's luck" binge...also I think this is what we are seeing when an inebriated player all of a sudden is playing the best poker of their life.
I suspect that in both cases we are simply allowing our brain to process micro tells and micro patterns by clearing our brain activity of all extraneous "static" and "chatter".
I have been in both places but they are both difficult for me to achieve; so in most tournaments I play the best I can "outside" of the zone or the flow. I can achieve the focused analytical zone much more frequently and predictably than I can achieve the intuition zone...but the best results I've ever had are when I'm playing in the intuition zone. Also, the most fun I've ever had playing poker were when I was in the intuition zone (and no...I don't get there by being drunk! ha ha)
so....in short I do know what you are speaking about and I hope I don't sound too much like a crazy wiccan crystal toting nut job.