Don't know, perhaps averaging over 100 regularly. Not saying it would but it just strikes me as odd that darts should be the only sport in the world where fitness doesn't improve the standard. We know you don't need to be an athlete to actually play but fitness helps with so many things other than just athleticism.
I don't think Fordham losing weight made him 'fit'.
Not saying I'm right but all evidence would seem to suggest that fitness should help.