You are improving your productivity by 'doing something else', such as 'walking for several hours in the forest'.
Banging your head against a problem for several hours while not making any progress is frustrating. Not because you are 'unproductive' in the sense of producing value for your employer or customers, but because you are 'unproductive' in the sense of not achieving the progress you desire.
Thus we want to improve our productivity. Not because we need to be productive in a capitalist sense, but because we want to be productive to have the feeling of achieving something.
Whether increasing your productivity comes in the form of going for a walk or getting rid of distractions doesn't change that.
Banging your head against a problem for several hours while not making any progress is frustrating. Not because you are 'unproductive' in the sense of producing value for your employer or customers, but because you are 'unproductive' in the sense of not achieving the progress you desire.
Thus we want to improve our productivity. Not because we need to be productive in a capitalist sense, but because we want to be productive to have the feeling of achieving something.
Whether increasing your productivity comes in the form of going for a walk or getting rid of distractions doesn't change that.