I think we may be talking about two different kinds of bias strips here.
Most of us use a strip of fabric folded in half and sewn onto our quilts, turn over to the other side and sew it down by hand or machine.
The bias strip makers (like binding tape) fold the edges in to the middle of the strip. These work great for stained glass, vines and such.
However, these only put a single layer of fabric on the edges of a quilt. This will not wear as long as a double thickness of fabric will :wink: The double thickness is only on the sides of these. :D:D:D JMHO