Question about Mug (Ninja)

I'm having a blast leveling NIN to max level, but I'm still trying to get the rotation down. So far, I'm at level 40 and still have a ways to go.

But for the skill Mug, am I supposed to be using that on cooldown? The tooltip says if I used it as a killing blow, it increases the chance for the mob to drop something extra. So, that led me to believe I was supposed to be using it as a closer.

However, I feel like it's a major DPS loss if I'm not using it as part of my regular rotation. So, I was just curious on the correct way to use it.

*before or as the killing blow

Basically just use it on cooldown.

Most of the time it's on CD, at lvl max you want to make sure it wont overcap your Ninki and if it comes to optimization you might end up delaying but that's when you know what you're doing, using it on CD anywhere else is fine.
You're not using mug for the "higher chance to drop" tbh.

I mean, unless you're out farming mob drops for crafting, item drop rate is entirely irrelevant.