What does this have to do with spudfiles?
They perform two separate test to find the most favorable conditions to get the desired result.
The first test is done with an empty "chamber". On high speed you can clearly see that ignition starts on one end and slowly works toward the other.
The second test is done with "obstacles" placed in the "chamber". this time the obstructions break the "wall of fire, for lack of better wording" Resulting in more surface area and a MUCH faster burn rate.
Im not a combustion person nor do i think i am the first to think this.
My Point is does putting a bunch of "junk" in your combustion cannon result in a more powerful shot

P.s No Grammer Police