A beep beep on your smartphone will distract you from whatever you are working on. You will loose your focus.
And according to Gloria Mark, once you are distracted from your original task you need 23 minutes and 15 seconds to get back to start focusing again. That is almost half an hour.
So imagine how many times in a day you get distracted by the beeps on your cell phone.It doesn’t matter whether you attend or do not attend it in real time, your mind will immediately get derailed as an element of surprise (who has sent you a whatsapp message etc) will keep your brain thinking on the notification instead of doing the actual work.
So if you want to use smart phones, then learn to use it smartly.