What is the Keijo manga release cycle?
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