No standard on the tractor but you are right for why it's shorter. Tilts the implement. You really want at least 3 holes. One (or 2) than 12". One at 12" and maybe one over. So I.E. 10, 12, 14 or 8,10,12. Something like that. There are times when you need a hole above, but usually you need at least one that is level (12").
I too apologize to the PO, but it's a similar topic.
