If you're right handed and start with the pointer in the centre of the screen, the base of your hand resting on the desk and palm/fingers covering the mouse, it

If you're right handed and start with the pointer in the centre of the screen, the base of your hand resting on the desk and palm/fingers covering the mouse, it is more awkward trying to move the mouse to the right than to the left. Movement to the upper right corner seems to require arm muscles.