Publishers are increasingly beset by a slew of challenges.

Fake news, a grudging dependence on social media platforms, the pivot to video—all of these add up to create an obstacle-laden environment for publishers trying to figure out a viable business model. Now, new data from native content discovery platform Taboola raises yet another difficult factor: a decline in the duration of US internet users' sessions on publisher sites.

Taboola reported that the average time spent with an individual page on a publisher site was 1.90 minutes in Q4 2017, down from 2.09 minutes in the first quarter of the year.

Despite peaking in Q2, time spent on individual publisher pages declined on a quarterly basis after that.

Taboola was also able to break down the data by device, finding that the average amount of time spent on a page was significantly shorter on smartphones—at 1.90 minutes—than desktops, at 2.62 minutes.

However, average time spent with individual pages on tablets actually increased during 2017, going from 1.81 minutes in the first quarter to 1.92 minutes in the fourth.

Last year, eMarketer found that consumers were spending more time reading news content on social networks, and because of that, publishers have followed them there.

Overall, many publishers are betting that content they distribute across social platforms, like Facebook, will drive traffic back to their own sites.

[Editor's Note: An earlier version of this story incorrectly attributed the average time spent figures to sessions on publisher sites, rather than to the length of single page sessions on individual articles on publisher sites.]