In a plane. What did you think I meant. I have a whole collection of planes with extra wide mouths, some I have even filed to get them wide enough. Why you might ask, because I can then see through the mouth while using the plane. In repair work many times you need to plane a patch down to the level of the original surface without going through it. With a wide mouth allowing you to see the blade taking the shaving you have much more control.
Here you see the tail end of the plane rides on the original surface, the blade is taking a very thin shaving and you can see what is happening through the mouth of the plane. This technique is also handy for leveling inlay, pegs, butterflies or any place you need to match a surface.