Remove phone from pocket to check time, then replace: 4 secs (I just timed it!).
Move wrist to see time: 1 sec
How many times a day do I check the time? Let's call it once an hour. Multiply that by 16 and you get 64 secs and 16 secs respectively. Over a week that's 448 and 112, then a year it's 23360 and 5840.
In ONE YEAR, you spend nearly 6.5 HOURS just checking the time on a phone, compared to 1.5 hours if you have a watch. That's a spare 5 hours you have to do, well, anything you want really. Okay, so I've just made the case for wearing a watch and not for wearing a smartwatch, but still...