I have no idea, as I've never tracked this sort of thing. I think I've had good and bad rounds both walking and riding. I prefer to walk when it's allowed, but only because I like to walk. There's really no quality of play variable involved in that decision.
BTW - I lived near Amsterdam for a couple years back in the 90's. Kan je nederlands praten?
I used to believe that I played much better walking but one thing I've noticed since I've moved is that the difference seems less. The real issue, IMO, has to do with pace of play. Before I moved walking fit perfectly into the pace of the courses - relatively little standing around. If I rode there was a lot of hurry up and wait. Here I find the pace of play a little faster for various reasons so when I ride there's less standing around.
FWIW - I do find walking easier on my back and joints than riding in a cart. I know it makes so sense since you are exerting a lot more energy walking, but the jolting of the cart and the getting in and out of the cart is much harder on my body - that can lead to better playing.
It makes very little difference in my scoring. I used to think I played better when I walked, that I stayed in better rhythm, stayed loose, all that jazz. I found though that my stats didn't support it at all in fact my scores were slightly better when I used a cart. I would imagine the slightly lower scores from riding come from lack of fatigue. This is especially noticeable when I walk multiple days in a row
I do prefer to walk, especially in the fall, winter, and spring. I like the exercise and lord knows I need it. When I play in competitions I tend to ride now because I need all the help I can get.
I'm sure you are right. In truth, I'm really not sure why or how he's slicing. I'm not a swing coach. I actually try to avoid offering any actual swing advice on this forum. I don't think I'm qualified to do so. It just sounded like he was having trouble and couldn't get the video thing to work. So, I was just trying to give him an easy way to get as much information about his swing as possible without the video.
Me thinks if he can upload a MySwing thread he'd be better off. But this was the best advice I had to offer on how to get some help from the many experts on this forum.
I sole the club, but lightly. For me, I feel like I want both worlds, finding the right grip pressure and balance per hovering and finding my reference point for striking the ball by soling the club. I also want to be consistent through all my clubs, and I definitely sole my irons.