So I can see several aspects that are being discussed here.

- Multiple characters:
We have nation role plays that have 20 characters per person, so what's wrong with 2 or 3 characters that you control to help flesh out your personal story. Some people want to explore a role play from multiple angles and in the RP that I'm in I have an Australian who loves silence and is a hardarse; and another character that is a mentally unstable, music loving nutcase. The two conflict each other but I know when I play them together I can show each side easily cause they're my characters.

- Collabs:
Love and loath them. Been in some where I'm a third character in the room and cause the two other players were impatient to write, my character was supposed to be a statue during their argument. That is bad collab work.
Good collab work is discussing all options and talking to all possible players. Even clarifying if a character is going to shrug or just say "yes". Long collabs are important as they cover all the important points, but as Gowi said, they are only as long as they need to be. If you have a problem with that, then maybe re-evaluate your view on the RP as everyone is entitled to their own spotlight moment, not just yourself.

- Player involvement
You joined the RP, it's your responsibility to post. End of story. Its not the GMs position to chase up players... EVER!