Black to Play 5-4
It can happen as early as the second roll.
In the position above, White’s builder on his 9pt has created many new point-making rolls for him. Those rolls include 21, 41, 43, 52, 54, 62, and 63, which make his 3pt, 4pt, 5pt, or 7pt. That’s in addition to the 31, 42, 53, 61, and doublets that White would have even without a buider on the 9pt.
Hit and split (X = 24/20, 6/1*) is a viable option against that kind of point-making power. Equally good is the non-hitting split (S = 24/20, 13/8). Run (R = 24/15) is very close.
Black to Play 5-2
In this third-roll position, Black was hoping to make his 4pt, 5pt, or 7pt. Instead, he has this indifferent 52 to play. Although White’s 11pt builder is not as potent as a 9pt builder, hitting and covering the 11pt (H = 13/11, 6/1*) makes the best use of a 5 by Black. It is natural to make the 11pt using the 2, and that means there are few ways to play a 5. Black’s second-best 5 is to slot his 5pt, but that play is a small error.
Mike