My show horses have a bridle path when it is show season, but not during winter because I just let it grow out. I like the look of a bridle path honestly, so I like it when they are in "Show dressing!" haha
My mare has a bridle path because I used to show her in 4-H and just got into a habit of it, plus her mane is super thick so it gets in the way. Right now it is about 3" long though because I have gotten lazy, but its way shorter then some of her mane but longer then the part that she rubbed out :(.
My gelding doesn't have one because he is mostly a trail horse and his mane is thin enough that it doesnt really get in the way
I clip just where the bridle lays, about and inch.
I do it becuase 1) I don't have to worry about it rubbing or pulling the hair. And 2) it gives my bridle the same fit every time... not that the hair grows out and it makes the bridle ever so slightly tighter... but I'm just picky I guess... other than that he is all natrual I don't clip anywhere else! (unless for a show)