Feet positioning

I was watching a youtube video on feet positioning and the guy said on EVERY board your front foot is supposed be in the middle of the surfboard. And if you have a three fin setup I believe its called a thruster setup your back foot is supposed to be slightly in front of the two front fins, but shifted all the way back for big turns which makes sense. But the front foot always being in the center on ANY board does not. What if your riding a longboard should your front foot be in the middle?