In this case, the plan called for starting with the most difficult part
to make sure things looked good.
We used cut-off pieces from the bookcase backing to cover a duct box. At this point, it was an experiment, but the planning rules still hold:
Look at the sections you are using and line up the bricks like they would be on a real wall section.
This means ‘half’ bricks are ends and should meet ‘full’ bricks on any outside corners.