You might need to hold a 10-minute presentation.
You might be tempted to think like this: “I need exactly 10 minutes, so I’ll use a timer.”
In my opinion, that’s a poor choice – at the end of those 10 minutes, you’ll need to take action on your smartphone to stop the sounds, and you’ll look distracted and out of focus.
You’ll still need to look at the timer occasionally because if you only know that you’re out of time at the end of the 10 minutes, you won’t be able to fit your talk into the allocated time.
A better solution? Use a stopwatch. Of course, you’ll need to manually check the time a few times, but you’ll look more professional.