I had this idea a second ago, I think it would be an improvement to the current /ads. Currently, you put however much currency you want in and it lasts for a day. So here is my suggestion for a revamp of /ads. Instead of being sorted completely in order of how much money was paid, they are sorted in random order EXCLUDING the top 3 which are sorted separately in order. Now, x amount of grass/skybucks is deducted from the amount of currency currently in your ad each hour, until it goes down to 0 when your ad is removed. This can be replenished like normal. For /skyblock, I think 1 grass per hour is a pretty good amount. And for /economy, 1000 per hour. I do encourage discussing the prices. (aka BUMPING MY THREAD)
I think with how little /ads is actually utilized by normal players, it'd be perfectly fine to extend the duration of the advert. I do think, however, that the order shouldn't be randomized and should work how the current one does.