What is the Keijo manga release cycle? Not sure if my phrasing is correct but does anyone know the manga release cycle of Keijo!!!! (Hip whip girl)? 

I haven't seen an issue for it in a while and the source I use to read it seems to only update monthly.

Does the manga actually release monthly? And how can I find this information for future series that I read?
Keijo is published in "Shuukan Shounen Sunday", which is a weekly magazine. 

To figure out what cycle a manga follows, you can use mangaupdates, which will show you the serialization magazine for each manga. From there you can just google the name of the magazine, and usually the english title will be an answer by itself, like in this case where "Shuukan" translates to "Weekly".

https://www.mangaupdates.com/series.html?id=101987