I'm curious to know what exactly Lamford's advice was.
In positions in which you are bearing in against an anchor, the pipcount suggests what your GWC would be in a noncontact situation. Contact will favor either you or your opponent. In typical positions, contact will favor your opponent, which means that if you double, he can take even though he would have a dead drop in a straight race.
I'm not sure what you (or Lamford?) mean by a position in which you would be bearing in against an anchor (20, 21 or 18 point?), needing to clear your midpoint, but where "your opponent has a good chance of breaking contact," and you "need a decent racing lead" to double. The following position, for example, would not be such a position:
The score (after 0 games) is: White 0, Blue 0
Move number 2: Blue on roll, cube decision?
| White | 88 | ||
|---|---|---|---|
                       | |||
| Blue | 67 | ||
| Position ID: 27YDAAO7OwMGAA Match ID: cAkAAAAAAAAE | |||
Blue's 21-pip lead isn't enough!
But whatever he or you meant, I agree with you that it doesn't apply in the "Stacky Gappy" position, where the side on roll is 40 pips behind.