i do not shoot off hand at all, un less i have to, just to tricky, can always find a rest of some kind. What you are saying is what i was thinking, site in as small as possible from bench and then get down to the nitty gritty, in dif. positions. Their is really no reason for off hand shots
if you don't have time to take a rest then it is usually a running shot, which years ago i might try, but wouldn't today