It was more obvious before the election, when the shilling was so prevalent that different accounts were copy/pasting the exact same phrases into their comments. And you would see a new point brought up, then an hour or two delay, then a response would suddenly show up in multiple places, copy/pasted into many comments, in multiple accounts.
But watch /r/all sometimes... you'll see a topic just suddenly start appearing. As an example, you think Rick & Morty grew popular on reddit organically? No, that started over the course of about an hour one morning, as a clearly orchestrated effort, and it worked.
It doesn't happen all the time... quite a bit of reddit is still honest and organic. But watch it carefully, and enough of it is manipulated that I don't put much trust in what I see there.