The evidence just keeps growing that multi-tasking increases the time you spend working and decreases the quality of what you produce. You end up doing more but getting less done. As this New York Times article points out:
“Indeed, multitasking, that bulwark of anemic résumés everywhere, has come under fire in recent years. A 2014 study in the Journal of Experimental Psychology found that interruptions as brief as two to three seconds — which is to say, less than the amount of time it would take you to toggle from this article to your email and back again — were enough to double the number of errors participants made in an assigned task.”
It’s not easy for most of us to just disconnect and focus on one thing, but the article also goes on to give some helpful tips on how to practice paying attention.