"mobile usage already significantly exceeds PC usage"
Following on the point about measuring the time split. How much is change from one form to other, and how much by increases in the availability of the newcomer.
Is this because in the past, we spent the journey on the tube to work looking at the newspaper or fellow commuters stubble, spent 8 hours on the corporate Windows PC (including an hour of lunch playing solitaire) then went home to watch CoronationEndersFarm.
Now we watch videos on our Android phone/iphone the tube on the way to work, spend 7 hours on corporate PC (and one hour on the phone checking social media), more social media on the way home and then the rest of the evening showing cat videos to our partners with one eye on the happenings in E17/Weatherfield/the Dales.