@Grimmycoffee I think it's more a case of laziness. The location of the path actually makes it a good firing position during the day, so arquebusiers were stationed there to take advantage of that. The problem was that the path was a also a pain to climb up to and down from, and walking back would have taken a long time, plus the one-man limit would have made it impossible to change guards quickly. What probably happened was that someone decided the path was a perfect unassailable location for arquebusiers, stationed them up there, then didn't bother rotating them back down for the night. The arquebusiers on their part would have preferred to stay up there anyway. Nobody actually expected a breakout attempt by men with swords on that path during nighttime.