Writing a full length novel has very little in common with producing a roleplay. Different objective, different theory, different structure.
In a novel your reader is expecting to be presented with 80,000 words and enters with an appropriate attention span. You have all the time in the world to tell the story you want to tell. Every scene can be fleshed out into an entire chapter if one so desires, and you can quite happily devote a thousand words to description without the reader batting an eyelid. Cutting down a novel is almost never challenging, since in even the tightest of texts large sections of the narrative are going to be ultimately gratuitous.
I present my submissions as chapters in a novel, but they really, really aren't. Nobody is going to sit down and read The Book of the Dragon like an actual novel, and as such I can't structure it as though it is. My chapters have more in common with a series of connected short stories, which brings about a considerably higher narrative burden. A good short story or RP (at least in my eyes) needs to contain a self contained character arc or plot development. It's all very well spacing these things about across multiple submissions (and I do quite a lot of this anyway just because it makes my penis hard) but the reader is not going to digest your work like that, so it's ultimately something of a waste.
What this means is that if, during a RP, you want to follow a particular plot or character arc or to explore a particular theme then it usually has to all happen at once. Half a narrative is of little use to anybody, and I suspect this is the reason that so many people elect to neglect a narrative component altogether. This is fine, except when you attempt to tell a story that is longer or more complex than the format demands.
RPs are very constrained in terms of subject material. There are certain topics that one has to touch on every week (although again I often endeavour not to for the aforementioned penis reason) and because submissions are intrinsically similar a shorter structure is beneficial. Once you cross 3,000 words you're in dangerous waters, and no matter how good your writing is people risk getting turned off by the length, since it is so much longer than they are anticipating.
The reason I'm so far over the line this week is simply due to an early error on my part. It was bad planning. When I create my narrative I ballpark how many words I am going to require to tell my story and plan accordingly. Usually I'm pretty spot on. This week I wasn't. Too many essential plot points, too many scene changes, in layman's terms I bit off more than I could chew.
I could chop then length in half, but that wouldn't involve tightening the writing or chopping out purple prose, it would involve completely retooling the narrative in order to be telling a different, less narrative consuming story. The narrative was written to be told as a whole, and as such I feel it would suffer more from being over pruned than it will from its somewhat bloated length.
So yeah... what was the question again?