Does the grain direction of the tenon matter in a round wedged mortise and tenon? I know that the wedge obviously needs to run perpendicular to the grain of the mortise piece or you’ll bust it open. But I wonder if the grain direction of the round tenon matters. I’ve never really paid any attention in my own limited work and oriented for best visual aesthetic. But this morning I saw Curtis Buchanan say that the grain of the tenon should be perpendicular to the mortise wood (didn't hear an explanation from him on why). So I did some google image searches and looked at way too many wedged M&T and it seems fairly random with most going parallel.
So it makes me wonder, does it make any darned bit of difference? Are there any situations where it would be better to orient the tenon one way or another other than visual aesthetic?
Here are a couple images I snagged off google to show what I'm talking about.
rmtparallel.jpgrmtperpendicular.jpg