When I host group games I often go into it with the mentality that every PC likes to feel like they're the star of the story, and that they'll be more invested in the story I have to tell of they feel this way. Few PCs I have encountered have liked being a supporting character to another PC.
With this in mind, I work to find a way to provide the illusion the PC is the focus of my story while simultaneously making it a group game where they can at their own discretion-'less the story guide them that way regardless-interact with the other PCs, as well as having their actions affect the events of other 'main character' type PCs.
This enables me, as a GM, to control the posting rate, in an albeit more subtle way than normal, and if done correctly, the individual PCs can feel like they're posting at a rate suited to their muses simply because this is mostly true. Some players can fall behind the main events, but still not affect the flow of the game for the other players.
It only gets bogged down when the players are teaming up or fighting each other, but usually my method was to avoid that entirely if at all possible by giving each of the players equally important but relatively nonconflicting tasks, each a full sized adventure waiting to happen, even should the players decide fo deviate from the plotted path-lovely part is, thers is always a way to bring the main plot back to them with ghe right planning.
My most successful RP followed this general strategy, and since it was halfway automated, it was less hassle than it probably sounds.
Now I admit, this usually won't work as well with games where everyone is mingling with everyone else, but for the more adventure based ones... particularly the system games, it is a rather useful strategy for me.
If the above made sense anyway.