Users' time spent with apps has increased 21% year on year

"Though 20% of apps are opened only once, people are becoming more attached to apps overall. According to Localytics data, the amount of time people spend in apps has increased by 21% over the last year. People are engaging with mobile so frequently that time spent with mobile apps now exceeds time spent on traditional desktop web. Certain categories are driving this increased time spent in apps. Here is a summary of the findings:
Overall time in app has increased by 21%
Users open an app on average 11.5 times a month, up from 9.4 a year ago (22% increase), while app session length has remained constant at 5.7 minutes
Social Networking experiences strong “snacking” behavior
Music has the greatest time in app increase of 79%
Time in Health & Fitness (a key feature in the recently announced iPhone 6) and Social Networking apps increased by 51% and 49% respectively
Time in app is a function of the average session length and the average number of sessions for an app. While the length of individual app sessions has been relatively constant over the past year at 5.7 minutes, app launches have increased from 9.4 times a month to 11.5. This boost in app launches has driven a 21% increase in time in app.
People are spending more time than ever with their apps, but certain app categories show a greater increase than others.
Music apps were the big winner with a 79% increase in time spent with these apps, resulting in an increase of 64 minutes per month compared to last year. As more people shift from iTunes to music apps such as SoundCloud and iHeartRadio, the time spent in music apps has drastically increased. These apps offer greater flexibility around music genres, playlists, and radio features. Most music apps also incorporate a social component, allowing people to share their favorite playlists. These reasons could explain why music has seen such a strong time in app increase over the past year.
Health and Fitness has shown the second highest increase in time in app at 51%, for an average 22 more minutes per month spent with these apps than last year. As the hardware specs for smartphones increase, so too does their potential to act as a health device. The recently announced iPhone 6 and iPhone 6+ comes with a new Health app that continuously measures motion data (which Apple claims is especially useful for people who climb stairs!). Similar features came with the Samsung Galaxy S5 released in May, including an integrated heart rate monitor and a fitness tracker. Increasingly, health features are coming standard with smartphones, as hardware becomes more advanced and consumers demonstrate an interest in fitness tracking."
Source:  Data from Localytics, reported on their blog, 16th September 2014

Note - Original post includes lots of great charts