Per the rules, I believe you're suppose to put them all in one listing anyway..that's what the rules said last time but no one really followed it..I did, but not many others..
However, I do find the 5 posts thing a little annoying.. what if you are a prop and wig commissioner, but also have cosplays, wigs, and props to sell. Then oh wait! They need something commissioned? Oh well, already have 5 posts, guess you won't get that ad up for needing something..kinda sucks and we should be allowed to make more.