Theres an old phrase that too many cooks spoil the broth.
My personal amendment is that too many characters makes novels a pain in the arse to write.
Currently, I’m telling the story of a skirmish in the war with the elves in Call of Herne, and I’ve got characters giving their perspective of the fight from four different angles – Callum and Jim on their respective transportations heading to join in, Roger Carlise and David Ward, two soldiers introduced in The Devils Regiment, who I liked and this decided to keep in the stories, The Girl, who is interfering but has been pinned in place by convenient plot device, and a side story in between chapters, that I don’t want to reveal – but is quite enjoyable in its own right.
Thus far it, has taken me 40000 words to get the characters onto the same continent. Go knows what I’m going to get up to now they’re together. I’m starting to sympathise with George RR Martin – I’ve become convinced he kills off characters for convenience more than anything else.