Probably the most important part there is not having the insides of the binding rubbing against each other and wearing out. Where you put it should only matter if you don't want to give up the 1/4" or 3/8" (for my walking foot) off of the quilt top. Actually, it might be more because you might be overlapping the first stitching line when machine sewing it on.
Unless I'm not understanding the question. It doesn't seem hard to keep extra batting/fabric at the quilt edge - you have to trim it somewhere - and sometimes I have left too much and have to trim with small scissors as I go.
hugs,
charlotte