I have been switching the editor to release mode when I build a release APK. I am not sure if this makes any difference. Can someone please confirm whether or not this is needed? I am talking about the setting on the the bottom right of the editor. 
Unless you do your own testing or get someone from Unity Technologies to confirm, it seems like we have to assume that setting only applies to the Editor (I got this idea from reading how the docs are worded: Unity - Manual: Debug C# code in Unity)
Also, when you build to a platform, the code is often re-compiled anyways and handled based on Player settings such as Exception Handling and Developer Mode.
I have been assuming that it can impact the APK so I have been switching it to release mode to be on the safe side for release builds as I don’t want to comprise on performance. Hopefully someone from Unity can confirm it doesn’t make any difference and save us the time. I strongly suspect it doesn’t make a difference to the APK based on the APK size. I have to look at the performance carefully to confirm.
You have the build configuration settings in Player settings. This is where you set the build config for a build, typically you can select between Debug, Release and Master. Depending on platform you can also choose other options such as prefer runtime speed or size, disabling exceptions or enabling them with full stacktrace.
This is what changes how your build is built, nothing else. Setting the editor in release mode only speeds up playmode or possibly the editor in general but I would assume at the expense of actionable error messages when there is a bug in the editor or possibly even your scripts.
Thanks. I will start saving time by not changing the editor mode to release then before doing a release build 