User blog comment:Sosprano/Sorcerer Kingdom Territory/@comment-31820190-20180614154725/@comment-45.56.46.26-20180716004118

Well, there are a few, like the Pleiades' Day and the Prologue books.

I'd rather have main story advancement, but the material for establishing the setting and stuff exist and if it can be compiled into books that's not a bad thing. Side stories can also be a good way for author's to "take a break" while still producing something of value to the audience.

So it's not a direct trade off between number of main story volumes and side story volumes.