Often things like the normal of the end effector is important. Other important factors are reducing power consumption (and thus motor heat) by taking into accou

Often things like the normal of the end effector is important. Other important factors are reducing power consumption (and thus motor heat) by taking into account system momentum and static torque on joints. I've even seen 5-joint arms in factories for when the robot needs to reach around something in order to drill a hole or install a component.