What is the reason for ZorinOS 16 r2/3/4?

[zorink]

We have updated the r3 post to include details of r4: Zorin OS 16 r3 and r4 incremental releases

Please note that it is not fully mirrored as the process usually takes over 24 hours to complete. We generally only post announcements when releases have been fully mirrored and are made available to everyone from the website.

As mentioned in the linked post:

@zorink

To avoid confusion in the future, we occasionally create revised .iso files (denoted with the "-rX.iso" suffix) which include the latest software updates pre-installed. They're primarily intended to make new installations easier and faster, but don't serve any purpose for existing Zorin OS installations.
You can see the details about these software updates by opening the "Details of Updates" in the Software Updater.

We don't plan to post further announcements about future "-rX.iso" releases as they are minor revisions based on the latest software updates.