It's easier to casually check what time it is on watch. Especially in a scenario where it's kind of rude to do so or your hands are full. Also having a timer ready to go, where with a phone there's several steps to get to one. You can do all these things with a phone but there's no real "cost" to wearing a watch and I miss it when I'm not wearing mine. Mines also automatic so I don't have to worry about it running out of juice like I do with my phone.