How the public feed works

I created 3 users in my network 


* Situation 1: User1 publishes a post in his "personal feed" with visibility = public. This post is not automatically displayed in the "public feeds" of User2 and User3, they are only displayed when they reload the home page. Is it necessary to configure something so that a warning of new content is displayed in the public feed?

* Situation 2: now User1 and User2 are friends (I comment that User2 did not receive an "on site" notification, only a notification by email (friendship request).

User1 publishes a post in his "personal feed" with visibility = friends. User2 receives a notification on site, however the post is not displayed in User2's personal feed, nor is it displayed in User2's public feed, it only appears in User2's "dashboard".

I'm not understanding how different feeds work and what would be the difference between being or not being friends with someone or just following them. Maybe wrongly, I think that in my public feed I should visualize those publications that are public and those made by my friends.

Can someone explain how the algorithm works?

If someone requires it, I can provide users and passwords to test.