At the start of opening a forum some would use post exchanges to get a few posts in and some content for new members but when should you stop using exchanges and paid posts? I have known forums to carry on exchanging posts well over a year old, What do you think about that? Should "Established" forums use post exchanges or not?
There is no need for post exchanges after getting well established. Because they will get some organic traffic . If they didnt get organic traffic then the forum wont gets up and it wont get active members if they stop doing post exchange.
Once your forum picks up, you can stop it. The first members are crucial though and, even if you might get lucky from the get go with some active members, some exchanges won't hurt.