After trying to build a number of simple apps and porting them on my devices, I learned several lessons the hard way.
Android SDK and Platform Tools non-default paths were causing major build times for me (30+ minutes). I just grabbed Android Studio and the reinstalled everything in the default location and that seemed to resolve the problem.
If porting the apk to your android device fails, first make sure the minimum Android API you are building against is the right one for your device. My Nexus 5X worked with API 6.0 minimum but the Samsung Galaxy device required API 5.1 minimum. The build time increase was not significant if you just go down to Lollipop (no need to support KitKat)
If you are doing build & run from Unity, set your device to stay awake while charging from the Developer options menu
If you look up tutorials or lessons online, be super careful about the version of Unity, Oculus utilities, and the Plugins that are recommended. A lot has changed in Unity with regards to VR support in the past few months. A lot of the content out there is already outdated
Each one of these bullets took some time to overcome - hope it will save you time - I'm starting late so maybe you are all done with this :smile:
