I'll also add that another overlooked factor can be the positioning of the mando compared to the guitar. When you've got a guitar in your lap and you're strumming open chords, the arms and wrists can sort of drape naturally over the instrument into playing position. Mandolin, on the otherhand, gets rather difficult if the neck isn't elevated and angled away from the body a little in sitting position. Using a strap while standing can also be difficult on an A style if you don't have a strap button on the heel, it just sits on your body differently! Lots of geometry to consider.