Well, I have a co-worker (actually my superior) who often sets his articles' slugs to expected / relevant search terms such as:
keywordA-keywordB-keywordC-keywordD-keywordE
I usually make mine closer to the article's title, e.g.:
robber-robs-XYZ-bank-10-million
He claims placing only the expected search terms as the slug led to better SEO and that SEO is more important than a human-friendly URL.
What do you think of the balance between human-friendly and SEO-friendly URLs and does littering your slugs with a few expected keywords actually lead to better SEO? Lastly, what is the recommended practice?