Suppose to have an article in an HTML Web page. The aim is to markup the content using such a schema (I prefer those provided by schema.org). Hence, one starts to markup the contents by following the schema.org/Article. The point is, if the article belongs to multiple sections, should one put each section in a separate span as follows:
<span itemprop="articleSection">Section1</span> -
<span itemprop="articleSection">Section2</span> -
<span itemprop="articleSection">Section3</span>
or it is equivalent to let them in a unique span like in the following?
<span itemprop="articleSection">Section1 - Section2 - Section3</span>
If your article is part of many different sections, then you should mark each one as a articleSection like in your first example: