Phish/Blogs are standalone point-of-time releases, meaning that they will only 'send once' within the specified timeframe.
Once this time has elapsed, any new users added to an ongoing campaign will not receive these steps if these have already been run within the campaign's Flowbuilder.
Policies and Courses do not follow this rule; therefore, the new user will still receive these subsequent Campaign steps in the same schedule that was originally set up.
Further information regarding Campaign Email Schedule can be found in the following article: Campaign Schedule Reporting – MetaCompliance