While there may be an upper limit as to how many apps people interact with over the course of a month, new data shows that the time spent actually using apps is increasing. In fact, the average time people spend in their apps is up by 21% year-over-year, with music, health and fitness, and social apps showing the largest increases.

The data also backs up what we’ve already heard from other sources. For instance, Nielsen recently said consumers were now spending an average of 30+ hours per month, and had an average of 26.8 apps installed on their mobile devices and the majority of our digital media consumption is now taking place in apps, accounting for 52% of the time U.S. consumers now spend with digital media.

Music apps have seen the greatest time spent in app increases, up 79% over a year ago, while health and fitness apps (51% increase) and social networking apps (49% increase) followed. The study says these shifts have a number of contributing factors. For example, the move away from iTunes to music apps like SoundCloud and iHeartRadio has changed consumer behavior, while mobile device hardware improvements have made them better health devices, prompting the increase in that category.

Meanwhile, social networking apps continue to see what the firm dubs “snacking” behavior, meaning it exhibits the highest number of app launches but the lowest session length.

This data is to remind app publishers and marketers that time spent in apps – the session length and number of app launches, that is – are metrics that also matter. After all, there was a bit of a hubbub earlier this year after comScore found that users simply weren’t downloading that many apps – the average smartphone user downloads 3 apps per month, it had said.

The bigger picture here is that while most users may not feel the need to constantly download and try new applications, they do spent a lot of time in those they already have installed.