First off, many thanks for the answer. I always appreciate it very much if you ( and the other writers ) take your time to have a conversation with us normal shlepps. But I want to point out that a recurring NPC doesn't need to be someone who fills a combat role, but can also be someone who tags along with the party and stays behind during the actual dangerous dungeon delves. Like, say, an old cranky sage who is needed to identify a very particular set of ancient information, to name just one example.I think recurring NPCs are a very good way to invest players into the story. I definitely felt that my players were much more into the story of CotCT, where they even started relationships with long-standing NPCs like Cressida and Trinia, than Carrion Crown, where I awkwardly had to insert Adivion Adrissant and Kendra into the plot at times when they shouldn't have appeared, if I had just kept the original outline of the AP.
This is a really good point. If there's been one recurring issue I've had across the APs, it's that the parts don't always tie together into a fully cohesive whole. Having recurring NPCs in any capacity can really reinforce that feeling of connectedness and go a long way toward making things feel like a single play in six acts rather than a series of six performances kinda-sorta based on a theme.