In fairness, I've done the separate posts to avoid mixing up posters and keeping posts to a shorter length in response to criticisms about those things.
Although it might seem counter-intuitive, addressing separate posters in separate posts actually makes your posts seem longer if anything (mainly because they're all right next to each other and we just see it as one big longpost anyways). Responding to multiple posts in one post reads a lot more smoothly and the quotes will serve to break up the post enough to where it's not confusing.
I guess avoiding mixing up posters make sense, but seeing as you post on forums so much I'd definitely try and get used to multi-quoting at some point. Usually I have a sticky note open next to my browser that I can just copy-paste stuff on, write my responses out, and copy-paste stuff back.