scant is difrerent in many situations.
However, if you don't want to do a scant 1/4" you certainy don't have to. However, #2, if you want your pieces to fit together you will. Just remember if you do a true 1/4" you have to account for the amount of space the fold and thread and needle size wil reduce the size. Its all in the fitting
Also if you take several of the same machines and same feet that fit it, the 1/4" will or might be slightly different. All in the mass manufacturing.