The first time I looked at that picture, I thought the same as Robert. Once Brian did the closeup, I see the bracing now. It can be an optical illusion for some of us.
Same here, Tom…odd.
Sounds like several agree that JJ was correct.
Huh? Adjustments are always made. Unprecise marking by 1/16" can compound or not placing the framing members exactly on the marks can throw off the layout for the sheathing. And then some of the boards will have a twist that has to be dealt with. Wood is rarely straight and that requires adjusting the boards as the sheathing goes down.
As a side note, I hear everyone complain about the crummy quality of lumber today, but forty years ago, we complained as much as today. Wood is not a precise building medium. Any of us who have done construction have seen a straight board take a turn within minutes after cutting the bands off a bundle. When I replaced my deck, some of the planks that had been held in a straight line for twenty years, immediately warped when no longer constrained.