Struggling to understand why you would use sat nav for a route you know well unless it's for warnings of traffic delays? On the occasions I find myself in an area I know I just ignore the sat nav direction and it seems to know what I'm doing and recalculates the route.
Ha ha I know what you mean. I sometimes take a wrong turning and being too proud to admit it I end up switching on the sat nav. Perhaps if you remove any route restraints it will come up with the route you know.