Nack (previous): "It is often right to strip the decreased-value midpoint after making the 7pt."
Can you please elaborate this little more and/or show some positions where this applies? This is the first time I hear about this and would like to know more.
For situations like these, real-position pair examples are elusive, because a change in distribution or race can have a major effect.
The feature position (61P-55P-62) is on the left (below). For comparison, an artificial position has been created on the right. There, Blue has played a 4 down and a 1 backwards (underlined) instead of 6 down and 1 forwards. The positions are distributionally similar, but there is a difference of 6 pips in the race (4 pips in the position plus 2 pips in the roll).
Using Snowie eval as arbiter, D (Down) beats S (Split-and-down) by .150 on the left, whereas D beats S by only .082 on the right. Granted, it is a bit more dangerous to split to the 18pt than the 20pt, and a spare on the 7pt is a bit more synergetic than a spare on the 9pt, factors that favor D on the left, but against that the race/timing difference of 6 pips should favor D about as much on the right. If we assume all that roughly washes, the difference in margins of .068 is telling.
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On the left, D beats Z by .030. On the right, D beats Z by only .017. The number that splits is identical this time: that factor is taken out of the equation. And yet D beats Z by more on the left in spite of the 6 pips difference in race/timing.
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Also, the midpoint and 7pt are inefficiently placed six points apart. You don't mind as much giving one or the other up as you would if they were not six apart. Ultimately, if you break your midpoint and end up with the 11pt, 10pt and/or 9pt instead, it/they will work together with the 7pt as part of the same prime. If, OTOH, you break your midpoint and don't own your 7pt, you'll have a nagging hole on your 7pt through which your opponent can escape, with nobody on the midpoint to act as a proper halfback.
Nack