A new University of Washington study found that, according to parent reports, while having routines, disengaging at a natural stopping point or simply having a battery die made for an easier transition when it came time for kids to turn off a screen, giving a two-minute warning actually made kids more upset when the screen was shut off:
http://www.washington.edu/news/2016/05/05/two-minute-warnings-make-kids-screen-time-tantrums-worse/
http://time.com/4321090/the-2-minute-warning-may-be-making-life-tougher-for-parents/
