When I first began writing in earnest, I found ongoing workshops and writing groups to be of great help. The comments I received on my own pages might or might not be useful to me, but I found reading other people's material--especially unsuccessful material--to be invaluable. It is so easy to see problems, and possible solutions, in other people's stories; it is easier to see you own problems and errors "by reflection," as it were.
Real-estate agents have a dictum that the optimum property to buy is the cheapest house in the most expensive neighborhood. Some writers have an equivalent rule that the ideal is to join a group where you are the least skilled writer. Easier said than done; most ongoing groups of skilled writers aren't seeking new members, and if they were, they probably wouldn't be seeking someone whose skill levels were well below the group's average.
I know one well-published and accomplished novelist who has been in the same writing group (of other professional novelists) for years. She still seems to get great value from it. My experience with critique groups has been quite different; for me the usefulness of the group has a natural lifespan, and if carried beyond that point the group dynamics tend to fall into a bit of a rut.
I also think that for many of us the usefulness of regular feedback wanes as we gain experience. Being able to present chapters of your first novel as you fight your way through it can be vital to the unconfident (Is this working? Does it suck? Am I crazy?) or to those who need deadlines to produce any work (though I don't think those in the latter category have much future as writers). But once a writer gains real traction with a novel, they are liable to outpace the reading and critiquing capacity of any regularly scheduled group.
I'm no longer involved in groups; I don't find feedback on individual chapters to be useful. (In fact, I find them to cause problems, as I will discuss in the next few days.) But I am blessed with a half-dozen great First Readers who read my first or second drafts and respond. I may not find feedback on chapters to be useful, but I find feedback on a whole novel to be vital, because it is at this level--the architecture of the story--where I'm still uncertain of my skills and choices.
Half of my First Readers are writers themselves, and can give feedback in mechanical and technical terms. But the non-writers are just as valuable, because they are simply responding as readers. "I didn't like Fred" or "I wanted to see more of Jill" or "I thought the middle was a little slow" are the kinds of comments that are often more important than the detailed critiques (and recommended fixes) writers are prone to give one another.
I may never be involved in another writing group; but thank god for my First Readers.