Waypoints are an important part of determining the logistics of a set. For example, if the girl is the guy’s sister in a 2-set, it is important to befriend the brother and prove to him that the PUA has good intentions. If the two girls are casual friends, upon gathering this waypoint, the PUA can determine whether or not the target is willing to leave her friend tonight, or if they need to drive back home together.
In the Mystery Method, waypoints are gathered during all the phases. The artist must have a general idea based on the feedback that he is getting from the girl on his level of attraction and comfort with her at all times.
When you run into situations you’ve never been in, try to look for waypoints by discerning the relationships of the people in the group.