You know Roger, how do they say:
"If you can wait and not be tired by waiting,
Or being lied about, don't deal in lies,
Or being hated don't give way to hating,
And yet don't look too good, nor talk too wise ...;"
I do only digital paintings, and depending of complexity of the scean, render could be from less then second, to several hours, longest I was waiting for render to be finished was 37 hours ... and I dont know until finish, will picture be good or bad, sometimes I wait for hours just to see that picture is not good, and to delete it, and start all over again ..
Patience .. :)