I have seen the Dash project, for example, having a lot of pages in just one thread, and they are one of the top threads in the altcoins section.
If a project has many pages and they keep very active does that guarantees the potential buyers a good investment with them?
The size of thread is the measure of the developers involvement in the interaction with the community in the forum. The more of the developers are actively answering the users doubts, the more people would question and discuss. Though a stagnant thread doesn't mean a bad project but there would be a communication gap. The activity can be in this forum, reddit or even on the github community. More active communication do happen in discord and telegram.