Is it okay to use his smartphone for hours

Is it okay to use his smartphone for hours? Is it okay to use his smartphone for hours? Can it be used for something good during lessons? Or does it just distract students from what they really need to do? I have an iPhone myself. I use it a lot. I mostly use my cellphone outside of school, but sometimes it is also used in school. For the most part, I think it shouldn't be over for hours. The phone distracts students too much, students just "suddenly" enter Facebook. But it can easily be used for something sensible in the