Last year my guild had two different instructors with two different takes on binding. I thought it was really funny. The first one said to use a 1 3/4 inch strip and a quarter of an inch seam. I don't remember what all her reasoning was. The next month the instructor said to use a 3 inch strip and a half inch seam because if you're going to put it on there it might as well be seen.
My general take is, do what works best for your project.