Regular Flat is a much more tricky corrective structure than a Simple Zig-Zag. In general we expect any corrective pullback to follow a-b-c structure. However, the first corrective leg A in Regular Flat is shaped as a-b-c. That essentially means that you can not be sure whether the first pullback shaped as a-b-c is all of the corrective structure or only the first leg down in wave A. After the first leg structured as a-b-c we get another move in direction of the main trend but it fails to violate the top of the previous rally in impulsive wave. That wave b up creates a double top. However, it is a very weak setup to fade that double top. Because there are two more variations of the flat structure, Running Flat and Expanded Flat, where wave B manages to make a higher high over the preceding top only to drop hard in the final wave C down.