It was a better bet for the Germans to "melt away" into the next trench-line back and then heave a LOT of nasty H.E. stuff into the recently vacated trench.
To this day, "FRIENDLY" position data, (and potential enemy "form-up" points), are always given to their supporting MGs, mortars and artillery. These "defensive fire tasks" enable beleaguered troops to call down Hell on their own position if things go really pear-shaped. Even a simple "shell-scrape" will offer some protection, even if a lot of that is "psychological". This practice continues to this day.
In the 1960s, the Australiantroops slugging it out at Long Tan called in artillery on their own positions. Anyone lying on the floor of the rain-drenched rubber-tree plantation was in some danger. Anyone standing up / advancing into that position was in deep trouble from shell splinters and chunks of shredded rubber tree.
Nothing "pretty" about it at all.