Moisture content, over straining, wood choice and it's properties, if laminated then the belly/back woods compatibility, bow design, pulling past draw weight, pulling past a problem in the tiller, bow width, bow thickness....and that is to name but a few.
1 inch is pretty good though. Set is actually desirable because a bow with no set is way understrained and we are trying to make a 90% broken stick! You want to be aiming for 1/2 inch to around 1 1/2 inches max.