All watch faces should have not only an interactive mode, but also ambient mode. The Wear OS App Quality guidelines specify that only 15% of pixels are illuminated in ambient mode.
Typically, the watch spends much more time in ambient mode, and during this time, conserving power is a priority.
Well designed ambient displays contain only essential information, and they minimize the number of pixels that are illuminated.
The recommended approach for implementing a component that alters in appearance
between ambient and interactive modes is to add two elements, each with a
Variant. Adding this at the Part* or Group level makes it possible keep
the number of Variant elements to a minimum.
<Group name="logo_interactive" ... alpha="255">
<!-- Hide these elements in ambient mode -->
<Variant mode="AMBIENT" target="alpha" value="0" />
<!-- Components to show in interactive mode -->
</Group>
<Group name="logo_ambient" ... alpha="0">
<Variant mode="AMBIENT" target="alpha" value="255" />
<!-- Components to show in ambient mode -->
</Group>