Prefer to visually separate menu sections with whitespace. Whitespace makes the UI look cleaner and request less cognitive effort from the user.
In the example below:
A uses dividers for everything
B uses a divider between sections
C uses only whitespace
A is too complex and distracts the user, but both B & C can be used on real-life user interfaces.
B puts more attention on differentiating the sections. C makes the UI look cleaner.