I don't really understand the poll question. Anyway, I think the DM decides if an NPC is recurring or temporary or permanent or whatever. I use them sparingly, unless the players are down one, then I will have a permanent NPC. Actually, when I ran Princes, we only had 3 players and I gave the party 2 NPCs, a priest and veteran, and they stayed with the party and slowly got better, but they weren't full classes. The healer got petrified by a medusa, and the veteran later was written out of the story when we had a 4th player show up. I think I had him turned into a wight and they had to kill him!