I chose butt joints myself, but I followed the guidance of having my backing plate extend in an 8:1 ratio along both sides of the joint. The strength of the butt joint is directly related to the length of the backing piece. I don't know of any structural butt joints that do not have any form of backing material to bind the two pieces. At some point of reducing a scarf ratio you effectively end up with a butt joint.

A shorter scarf ratio then 8:1 may work, but I doubt something as short as a 1:1 would. Nor do I think it would be easier to cut or assemble. Be it 1:1 or 8:1, you still have to perform carefull angle cuts, and not have the pieces climb one another when bonding. Only when the anges are so long as to result in long thin pieces of wood does the length of the scarf become excessive, from a woodworking perspective. A limit which would vary with each individual. Probably an infinite length scarf is strongest, but that would simply be a laminate Which would result in no length extension of the piece, the purpose of scarfing in the first place.