If both sides are the same thickness I don't think it matters as long as you are consistent.
That is too cool, one way to save materials. First time I have seen that, but it has been years since I was in business. I always made all my fluted trim anyway. New things all the time now days.Sorry, this is the only ones we are exposed to here. It contains both flutes on the same board. https://www.homedepot.com/p/EverMar...Jointed-Casing-Set-7-Piece-620-662C/202087162