Why don't new posts in the advertising sections relocate the post to the beginning of the forum like all of the other categories?

Also, why do you have to wait so many days before placing another post in that category?

Because this way, every free ad is placed in the oprder it was posted, no matter how many other posts are posted to it, or if the person tries to bump it, etc. The 5 day limit is so that everyone gets a chance to post there are one or two people don't flood the forum with offers. How many special offers can one company run per week anyhow. One ad per 5 days seems more than reasonable, eh?