Steps to reproduce:
1. Open project "anim_vert_example.zip"
2. Build for device
3. Open up Unity Profiler and select TimeLine view.
4. Deselect 'record'.
5. In the timeline, zoom in with the scroll bar on the 250 'AnimatorControllerPlayable.PrepareFrame' tasks until you can see which cores they are executing on.
6. Notice that the jobs are not executing on all 4 cores. Sometimes only 2, sometimes only 1, and the rest of the worker threads can idle.

To see expected results:
7. Press Play to run the project in the editor.
8.Select 'Profile Editor'.
9. In the timeline, zoom in with the scroll bar on the 250 'AnimatorControllerPlayable.PrepareFrame' tasks until you can see which cores they are executing on.
10. Notice that on PC the jobs are executing on all the cores.

Reproduced on: 5.6.5p4, 2017.1.3f1, 2017.2.1p2, 2017.3.0p3, 2018.1.0b4