In brief
Users with smartphone screens measuring 5 inches or more spent 23% more time on apps than users with smaller screens. The study also found 21% more app openings and average sessions that were 3.53% longer.
Many users are upgrading their smartphones to models with increasingly larger screens, reflecting the current smartphone trend: most mainstream and flagship phones have screens measuring 5 inches or more. Recently, a market research firm specialising in apps published a study examining smartphone screen size and time spent using apps, finding that the larger the screen, the more time users spend on apps.
The firm studied 271 models from the popular Samsung and iPhone ranges, spanning the Galaxy S3 and Note 2 from 2012 through to the latest iPhone 6s Plus and iPhone SE. The study found that users with larger phone screens spent more time using apps. Users with screens measuring 5 inches or more spent 23% more time using apps than those with screens smaller than 5 inches. Their average monthly time spent using apps was 65.93 minutes, compared with just 52.23 minutes for users with smaller screens.

Users also opened apps 21% more often on larger-screen phones than on smaller-screen phones, and their average session lasted 3.53% longer. The analysis suggested that larger-screen phones on the market generally offered stronger performance, making them powerful tools that users were more inclined to use. If you are addicted to your phone, switching to a smaller-screen model might perhaps help you kick the habit.
http://unwire.hk/2016/05/07/bigger-screen-more-time-on-apps/mobile-phone/