Ive released 2 marketplace packages, both released within at least a month of submission with there only being a few hiccups on the first submission.
As far as i am aware there are a few variables that Epic take into consideration when releasing even approved content. They only want to release gradually so as to not burn out so to speak. Also if your submission has similar style content to an already released package im pretty sure your “spot” will be given up to content that is unique and fills a particular need or niche at that time.
Both my packages were unique in the sense that there wasnt anything like them on the marketplace when i submitted.
At least that is my take on the situation and i kind of agree with the way they are doing it. This way more quality content can be released instead of having a whole bunch of similar stuff that may not even be relevant to the markets needs at that time.