I for one take pride in my characters, and many of them have a formed backstory. I am often quite lazy when it comes to the creation of a truly fleshed out backstory, however, and that tends to take me a lot of time to get through. I am currently in the middle of the backstory for my Draenei character, currently sitting at 5000 words, looking pretty good so far, making use of the unknowns of Argus to sculpt countless of my own stories.
Unfortunately, Auchindoun is a key part of the backstory, though the lore on it is completely tangled up, so it's a huge pain to get through, and I'll likely get it wrong in a few spots by the time I'm done, so I'll need to extensively check up on the work by the time I'm done, to ensure all the final knots and crannies are untied and flow correctly. Following him, I have another few I'll need to flesh out too. Fun fun, being a roleplayer, though it gives you a lot more purpose with this game once the game itself grows a little old at certain times.
It's really dependent on how I feel. Sometimes I end up writing a whole novel, sometimes a little excerpt. (Mostly for my own benefit if it is really long)