I mean it would depend on what platform and all i suppose, but the devs of the project I'm in does lots of "coordinated shilling", things like raiding a telegram chat or commenting on twitter posts.
I really don't know how effective they are? What is the main marketing in crypto anyways?
Technically its SPAM, A massive amount of spamming. If you see a team of shillers specially the paid one they work in a coordinated manner, You see them talking about a certain coin and how that coin makes them millionaire in just 5 minutes. In turn newbies and believers will search for it and invest on it thinking they can expect the same returns like those shillers.