(Figure 611a)

See Figure 611a. The focus is boasting onto the back third of the side wall. If the strike point is anywhere in the coloured areas, a viable boast is not possible. Yes of course there are viable boasts but only beyond the short line.
Viable boasts are possible from the back triangle. The possibilities are limited from position #1. The sweet spot is marked. Be reminded that a viable boast is possible if the ball contacts the side wall in front of the sweet spot. Boasts are not viable deeper than the sweet spot.
(Figure 611b)

See Figure 611b. Position #2 is along the ball flight from #1. Same ball flight, same sweet spot. Any strike point between 1 and 2 has the identical sweet spot.
The opportunities are quite limited to the back third.
(Figure 611c)

See Figure 611c. As the strike point moves further away from the diagonal the opportunities open up. The geometry for strike point #3 is shown.
Again, viable boasts are available from the sweet spot and beyond. Shots deeper than the sweet spot are not viable.
(Figure 611d)

See Figure 611d. Again, the sweet spot remains constant for all strike points along the flight path from 3 through 4.
Not shown but moving the strike point even closer to the back corner will move the sweet spot deeper.
In this and previous discussions boasts are assumed to travel as a laser beam. Angles of incidence equal angles of reflection. And although three wall and other interesting shots may reach the front wall fairly, for the purposes of refereeing, viable boasts are those that would reach the front wall directly after contact with the side wall.