Military Box Pleats: how much "excess" to cut-out of the fell?

[slohairt]

If the pleats are stitched to the bottom of the fell and you do proper steeking, then why do you need to leave more than 1/2 inch? I realize there is more bulk due to the extra fold but I just don't understand why you can't cut out the bulk the same as a knife pleat. Someone in the know please fill me in. What tartan are you working with by the way?

Royal Canadian Air Force.