If I understand correctly, you are asking how many off-site posts, such as blog entries, articles etc... you should post every month.
There is no recommended quantity of posts, as the quantity will vary depending on your trade, the channels in which you're posting, as well as the content you are posting, and finally the number of keywords you are trying to rank for.
However, you can use this as a guide: every month, the totality of your posts should cover the entire spectrum of the keywords you are trying to rank for. Hopefully you already have a list of 15 to 20 keywords that you are working on. In total, all of your combined posts every month should cover all of these keywords.
Finally, search rankings are not calculated based on your quantity of posts. Rankings are calculated based on quality, relevance, user engagement (i.e. how much time people spend reading your posts) and consistency, among other factors. For this reason consistency is a must. If, for example, you decide to post 3 days a week on 10 channels (Blogspot, Twitter, Ello, Insta, etc...), then you must consistently produce high quality posts 3 days a week on all of these channels.
