Thank you for your answers!
@Ivo:
>>> Try the group policy "Remove common program groups from Start Menu" in Administrative Templates -> Start Menu and Taskbar.I know this this setting. It does have a negative side-effect, because it will remove the "Public Desktop" as well and I don't want that!
@Gaurav:
>>> Also, what if you redirect both the common programs folder as well as the common Start Menu folder using the 2 Classic Shell Policy settings for both?As I did mention in my first post, I got recommended to keep/use the default Microsoft folder-redirection instead of the integrated-ClassicShell redirection. (="Common Start Menu Folder"-Setting)