Today that plan is worth

The dotted red line is what you would hold today had you sold then. The regret figure appears in the comparison below.

A model of what this rule would have done, not a recommendation — weighting your buys does not reliably improve your cost. Without the hold, a 0× band skips the purchase and that money is never invested. The faint dashed line is the same plan with flat purchases; the Cost vs flat figure is the like-for-like comparison, because the two plans need not invest the same amount.