App developers might not like hearing the news that one out of five mobile apps gets used only once. But the figure is actually an improvement from four years ago, according to data from Localytics, an analytics and marketing company. Four years ago, Localytics found, a quarter of all apps were run just once.

The apps most likely to be opened repeatedly fell into the weather and social-networking categories. These tend to rely more on constantly-updated content, which can prove addictive. Even some utility apps can be addictive if they do one thing very well.

Meanwhile, sports and game apps were most commonly one-use-only, likely due to the volume and variety available. "Both of these categories rely heavily on first impressions to engage users or risk losing them to a competitor," Localytics wrote in a blog post. "Games in particular have a nearly 50 percent chance of never being opened again if a user doesn't return to the app within 12 hours." 

Interestingly, Android users engage with their apps more frequently than iOS users engage with their apps. Localytics said the discrepancy may be due to iOS users "suffering from app overload," which can "weaken retention," but I'd venture to say it has more to do with the fact that Android screens tend to be larger, which makes them better suited for consuming news content and playing games.