Well, keeping in mind that he has to roll to attack for each of the goblins, you are right. If you have ‘great cleave’ you can keep killing goblins until you either miss one or hit it and don’t kill it or run out of Goblins. Or in other words, until you fail to ‘drop’ one.
If you just have ‘cleave’, you get only one extra attack. See below…
(With just cleave)
Roll an attack on Goblin A, if you hit it, roll damage, if you ‘drop’ it, roll a cleave attack on Goblin B.
If you hit Goblin B, roll damage. You’re done.
(With great cleave)
Roll an attack on Goblin A, if you hit it, roll damage, if you ‘drop’ it, roll a cleave attack on Goblin B.
If you hit Goblin B, roll damage, if you ‘drop’ it, roll a great cleave attack on Goblin C.
If you hit it, roll damage, if you ‘drop’ it, roll a great cleave attack on Goblin D…
(Continue until you are out of goblins, or miss one, or don’t ‘drop’ one).
-Tatsu