[entrepy123]

Fullscreen (or, as is my preference, "hide menu bar automatically" and "open window to maximized not true fullscreen mode") is useful for presenting a full display cleanly, when the contents to present is exactly 16:9.

Otherwise, the menu bar makes the contents not truly 16:9 or awkwardly shows distractions/leakage in the form of the menu bar.

Critically, if contents being presented is true pixel perfect 16:9 ratio and the window is not "fullscreen" or "maximized with hidden menubar", then the aspect ratio gets messed up, ruining what is otherwise perfection through a slice of "missing" content along one edge.

Indeed, more for presenting than actual task work IME.

Nice thing is this clock can show on other displays, too, in multi monitor setups, e.g. when auto-hide-menu is enabled. So sweet.