minilogoguy18

Arms at 45 deg btw is much better for deformation and animating. The shoulder and pecs are at rest in that position.

maybe the shoulders are more natural at 45 degrees...but a T-Pose puts the arms approximately at the mid-point of their full range of motion.

No, to get the arms in the hands up position you're rotating your arms on a totally different axis. 45° is the middle of a global Z axis from a front perspective.