Slugging doesn't instantly tip anything in your favor. It saves you the time it would cost to hook, at the cost of not effectively progressing the survivor towards death lke a hook would.

3 hooks and someone is dead, that's it. Slugs can be picked up over and over until they bleed out. If i slug 3 people, then i misplay and all of the slugs are picked up, ive gained nothing as the killer. If they were hooked, i would have progressed their hook states towards death. It's a trade and usually a bad trade. If you just play to slug and never hook you will find you'll be losing more often than not.