By the way, 4 will either drop in late October or at some point in November. If early enough, maybe 4 and 5 in November. If not, 5 will see release in January.
It might be good. I considered joining one when I was writing, but I've since stopped, so I didn't end up doing it.
They offer very helpful advice and you can be sure to develop your skills.
It's challenging, though, since they'll really push you to develop your abilities, but I feel that for serious writers, it might be worth it.
One of the more popular ones out there is Scribophile. I had considered joining it.