Depends on what side of the ambush your talking about . If your doing the ambush , the guerillas fighting the Japanese had a 7 second rule , dont engage the enemy for more than 7 seconds before your on your way out . This was because after 7 seconds , the surprise is gone , and they start to get their bearings , and come after you . If your on the receiving end , snipers are a pain in the butt , even for trained soldiers , you might have to stay under cover until dark ……..and hope they dont have night vision . Selco talked about having to spend an unplanned stay to avoid snipers .