My plumber buddy said something about carpet seams that stuck with me

We were having a beer after finishing a duplex job in Phoenix last week, and he asked why we always seam carpets parallel to the main light source. I gave the usual answer about hiding the seam, but he pointed out that in bathrooms, tile guys run the grout lines toward the light to make them look straighter. Made me think maybe we've been doing it backwards in some rooms for years. Has anyone ever tried seaming perpendicular to a big window just to see if it actually looks cleaner?