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Is it guaranteed that every frame takes 16 ms in Android?

The refresh rate depends on the display. Newer displays have high refresh rates and even variable refresh rates.

Of course it also depends on what you mean exactly, on a 60Hz display a new vsync fires every 16.6ms, but the all may take more time and miss a frame 

Also things are made a bit more complicated by the fact android gives apps a longer window by firing vsync ahead of time 

Tl;dr don’t assume 16ms and if you need to sync with the display, use the Choreographer API

There is test snippet on Android CS, Compose section:
```// Forward the clock by 2 frames: 1 for toggle and then 1 for count
composeTestRule.mainClock.advanceTimeBy(32)```
It apparently assumes each frame takes 16ms. So, I assume this test could fail on some devices.

Sample: <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/ui/ui-test/samples/src/main/java/androidx/compose/ui/test/samples/MainTestClockSamples.kt|https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/[…]java/androidx/compose/ui/test/samples/MainTestClockSamples.kt>

Tests are setup with a special monotic test clock that guarantees a frame delay of 16ms