The Chinese chestnut trees growing on my property seem to know how to maximize their energy expenditure.
Normally there are three nuts in each spiney burr. The burr on the left in the following picture has opened but still retains the three fully developed nuts peeping out. The burr on the right has one developed nut and two blanks.
In the following picture each burr has one blank and two developed nuts.
And here is one where none of the three nuts developed.
And the following picture show an array of blanks.
The following shows an array of developed nuts.