Question: I have a bloger system with this type of address:

```
www.example.com/xxx

```

each blog has its own content.

Should I add blogs to sitemap.xml (for example as a static sitemap) or only all content is enough?

I want search engine recognized blogs.

Answer: 
Adding a category to a sitemap is up to you. To answer this question you must ask yourself "do I need to rank my categories in Google?"

If yes then add to sitemap and index them. 
If not then don't add to sitemap and noindex them.
Your category archives are more important than individual pages and posts. Those archives should be the first result in the search engines. The more likely your individual pages are to expire, the more this is true.
(<https://yoast.com/category-seo/>)