An interesting theoretical discussion, for sure.
The last motor I wound was for a science experiment in junior high, but I did sleep in a Holiday Inn about 5 years ago
One obvious advantage to winding both strands at the same time is both will be the same length when all is said and done. That means that they will be contributing equally to handling power in the motor, and will be producing exactly half the total magnetic field in the motor. Maybe it's just for ease of calculation, but there has to be some advantage to having a balanced setup.