The only communities that have mods on 24/7 pay them for it. No matter if people are -usually- on at a time during the day, there will be tons and tons of exceptions.
Now, the other side of this coin is that not everyone can handle instantly judging the integrity of someone across the internet. I'd rather have fewer mods than a mod that bans at the wrong time, because that's quite possibly the single best way to lose users. That said, I'll observe and see if even more mods would improve the chat experience at this point.
For persistent trolls, you simply tell an Admin. We do IP checks and I can network-ban. Normal mods cannot do this and have never been able to. Sometimes you, the user, will have to endure a troll because access like that is limited, for a good reason.