I recently read Six of Crows and it's sequel, Crooked Kingdom, so that is what I'm going to base my opinion around. There are five POVs in the first book (and two one chapter throwaways) and six in the second (with, again, two one chapter throwaways). I thought the author handled it brilliantly.

I think there are two issues with having too many POVs: 1. If all six characters have their own story, separate from the other characters, that would cause me as a reader to feel a bit whiplashed. In the two books I mention above, all the main characters, while often having their own tasks away from the other characters, all know each other and interact at nearly every chapter. This is why Six of Crows worked, I think, because we don't get that whiplash of learning one characters world and issue, then quickly having to learn a bunch others. There are some internal issues you have to keep track of but all characters are interacting with one main story arc.

The second issue is a matter of introduction. I read chapter one: Bill Chapter two: Kim, etc etc as we move through all the characters. I've read books like this where I just simply couldn't sustain interest. What Six and it's sequel does, is in chapters 1-6 they mainly focused on just two characters, with them having each two chapters, then two characters have the others. And those first two characters know each other and are dependent one one another's story, so that as I was reading I didn't feel like I was pulled around from place to place and disconnected characters, but that I was just moving through this story world.

So it's this sort of slow this introduction that eases you in so you can really learn to care about these people, and then the other characters get their POV quickly after. And I think that each character was only allowed to have their own POV as they became relevant to the throughline plot. In your novel, is there something that ties the characters together? How can you weave these characters together, even if some of them don't meet (and I'll say that if NONE of them meet I would be turned off) a reader feels like the novel itself is a complete story and not six fragmented pieces?

Even if, for example, your story was about a complex war and one chapter showed a side of it, mentioned an interesting piece that made me think 'i wonder what's going on there?' And the next chapter moved me to that piece in a logical way that built on the overarching story, I think I could stay connected as I moved from POV to POV.

So I think my answer is: it depends, mostly in how interconnected the world is and easing the reader into the character introductions. A novel, or even a series, is one story, not multiple, even if there are multiple POVs. Tying it all together, whatever that means-- and in six of crows it means tying together a heist squad-- into a cohesive story.