Actually a serious question. WWII, SOP was to dig one before before bed, and fill it in, to deny to the enemy in the morning. This drastically slows advances. Fail to do so, and one artillery barrage and you're screwed. A whole lot of work, but the alternative is ugly. On the other hand, let the enemy advance a mile or three, hit them when they're exhausted from marching, adrenaline crash and digging.......
FQ13