Quite some time (sort of). The forum I used to be in had "playwrite" style RPs. Not all of them but a good deal of them when I began RPing. RPing became one of the major things of that forum.
Example:
*Muramasa walks into LCB's room and takes his books*
Muramasa: lolol I have your books.
LCB: Don't touch my books.
The content wasn't like that, but the format was. Eventually I started to pay attention and began doing the third person narrative style RP posts.