RO,
This is a great article:
https://moz.com/blog/15-seo-best-practices-for-structuring-urls
See:
#6
Shorter URLs are, generally speaking, preferable. You don't need to take this to the extreme, and if your URL is already less than 50-60 characters, don't worry about it at all. But if you have URLs pushing 100+ characters, there's probably an opportunity to rewrite them and gain value.
I tend to not have a category in my URL and see this practice most of the time when surfing around.
Also, see this article:
https://yoast.com/wordpress-seo-url-permalink/
See:
Should I use the category in my permalink structure?
If your domain name is nice and short and you use short, yet descriptive category names, you can easily include a category in your permalink structure which can benefit your website, but beware: if you end up with a lengthy slug and category name, it will make sharing the URL more difficult and won’t have much added value in Google.
If you decide to use categories in your permalink structure, make sure that you only select one category per post. For some more information regarding using categories in your permalink structure, I advise you to watch the following video by Matt on this section.