I noticed the 506 posts in one day today also. If I did my math correctly, that barely seems possible.
If you figure someone sat online for an entire 24 hour period, that's 1,440 minutes. 1,440 divided by 506 posts = 1 post every 2.8 minutes.
Since it's unlikely someone would post for a continuous 24 hours, use 12 hours (which is still a lot for someone to do). 24 hours x 60 minutes = 720 minutes. 720 minutes divided by 506 posts = 1 post every 1.4 minutes.
I've seen this member's posts before...she isn't one to 'cut and paste' the same thing repeatedly. Her posts are thought out, honest conversation which takes time. Being able to post 506 times in a 24 hour period and still have some life away from the computer, doesn't seem likely (humanly possible, but not likely).
After doing some review, it appears that a lot (maybe most?) of those posts came from the Games, Jokes & Fun forum for counting to one million. So are these not included in a person's post count but are showing up on the daily stats?