Someone asked me why I fold the magnetic snap prongs outward, and I didn't have an answer other than: "that's how I've always done it". The prongs can be folded inward on top of each other, but I have always just folded them out. Not sure why, other than habit.
So I did a test to see if there was any difference.
What I discovered is there is a more visible bump under the fabric when they are folded inward. You can also feel them more than when they are folded outward flat. Neither of these things would be issues for snaps that aren't on a flap or somewhere very visible.
I do like that they out of the way more if they are folded inward. This would be useful if the prongs are in the way when you are sewing.
For now, I'm going to stick to the folding outward method. Most of the things I make require a snap on the flap, and one thing I always try to do is make sure the back of the snap isn't making itself obvious.