Take todays lesson more as a “rule of thumb” rather than a hard and fast rule, but I recommend that when you are stacking on a door that all operators have their muzzles pointing outboard or away from the wall. This allows everybody to immediately engage a threat that may exit the door or approach from outside the structure.
If you have your muzzle staged “inboard” you run into the issue of possibly having your weapon pinned if the guy in front of you backs into your arms. You also have the danger of “lasering” the man in front of you if you try to transition over to the opposite side.
As I said this is just a tip; you may have a situation where you find stacking “to the inside” advantageous. I have done it on occasion when I knew I was going to make entry to a particular side. If the guy in the above illustration knew that he was going to move to the right upon entry than he may find it “flows” smoother to stack inboard because he wouldn’t have to perform a “U” sweep to avoid lasering the man front of him. The most important thing here is that you at least consider the issue. It is always better to make a conscious decision than to be caught by surprise.