One thing I learned from reading J.Oconnor was to use any kind of rest you can find, any time you can find it. That said Ive never shot off sticks, but can definitely see the advantages to early practice off sticks.
Ive done pretty much everything else in Africa, offhand,with a rest, sitting,off the PHs shoulder etc�but sticks were just coming into vogue about the time I was tapering off the African hunting.
