There is no hard limit, but make no mistake, there is a limit, especially in a short time frame, where if the staff or (and this is more likely) the users notice you creating several threads, they will get reported and likely merged or removed.
If you have a lot of topics you want to discuss, either space new threads out over several days/weeks, or create more generalized thread titles/topics where you can discuss multiple related topics in fewer threads.
Now, if there is enough demand for a variety of subtopic discussions in the same general topic (ex: tv shows, bands, movies, etc.), then I am more than willing to consider creating new forums for those topics.
The demand would have to be there and there would need to be several (or a lot) of users interested in and willing to post in those kinds of threads.
In the past, when these situations have happened, I tried creating new general topic forums (Gaming Zone, Movie Zone, etc.) only to see them rarely used by more than 2 or 3 users.
In most cases, it's just better (and easier) to create a single thread with a general title/topic such as "Movies you have seen lately" or "What books are you reading" rather than make a new thread about each one.
More importantly, most users are more likely to read and post in general topic threads like that unless the subtopic (specific movie, tv show, music group/band/singer, etc.) is very popular with the users here (ex: Walking Dead, Game of Thrones, Avengers movies, etc.).
