Mine do have to learn that the table ENDS lol. I do allow them to discover that while I am there to catch them. Fear in that instance can save them...I never leave them on a table unattended but I have seen some dogs LEAP off grooming tables, noose or not, or fly off the judging table and run around a show loose, and that is FRICKING TERRIFYING...
I like mine to learn the table is not scary...but the DROP off the table should be respected. So I hold them while they nose over the front or back up up up to the edge in back then say WHOOPS! WHAT HAPPENED? OMIGOSH!...and reward them with praise or food, etc for staying on it.