Either!
The ovens perform so well, you really don’t need to close it off – it’s a customization preference. When your firebrick gets to 900+ degrees, the bricks retain the heat for hours!! Rule of Thumb - as long as 60% of the oven is open, you are able to operate the oven effectively. The Perini Oven on the Photo Gallery is a perfect example of closing off 40% of the front of the oven.