If it calls for a 1/4 inch, then I would do that. It should say if they want you to only use a scant 1/4. Until recently patterns were always cut for the regular 1/4 inch seam allowance. I don't understand why that has changed, but since it has we just have to go with it I guess. If you aren't sure about your 1/4 inch then I would do a test piece and make sure it is accurate before starting the project.