Thanks for the links! I think my definition is essentially the same as John Cleese's in the first article. I somewhat disagree with Blackshaw in the second article about the relation to productivity. Open mode is compatible with having a goal, as long as you are not overfocused on a particular approach to that goal, so it's not necessarily unstructured playful exploration. Closed mode can make you less productive if it results in obsessiveness, e.g. repeatedly checking email for updates, or skipping breaks and thus getting unnecessarily tired.