Correct, in the battle of 8 mobs (without jumping in mobs), you can kill them all within 4 rounds if you use Hagendis Beating. But if you still use Hagendis Hit, then it would be 8 rounds.
Noticed: it works only on mobs which you can kill in 1 shot with Hagendis Beating without Hot fire.

If you can kill mob in 1 shot with Hagendis Hit, but not with Hagendis Beating, unless you use Hot Fire as combination. Then that same battle would be ended in 6 rounds if you use Hot Fire and Hagendis Beating, and that is still faster than Hagendis Hit with 8 rounds.