My parents gave us complete freedom to have our rooms how we wanted, the only rule was that there had to be a 3' wide "fire safety path" from the door to the bed. I am now a very organized person - almost a neat freak so I am not sure about the window of opportunity theory.
I carried this on with my kids (as difficult as it was for me) with the added rule that there could be no health or safety hazards, and I now have one neat freak and one...not so much. Funny thing, the one that's messy now used to be very fussy about putting everything in its place, she gave that up when she had to share a room with her messy sister and now they have switched.
