Ben Brooks on The Brooks Review writing about removing mental overhead on his iPhone’s home screen:
The most immediate change that you notice: there is a lot less mental overhead involved in using your phone. If you take a look at my current home screen you can see that I have only 16 visible app icons, and 3 folders for 19 icons total. It used to be that the first page and dock were full of individual icons, and the second page was entirely folders.
I employ a similar tactic (though I’m not yet using iOS 9). Not only do I have all notifications off (save for SMS) but I also only have three rows of icons on my home screen. On an iPhone 6 this means two completely empty rows.
All other apps are shoved to other screens and I simply use Spotlight or Siri to open apps.