I normally wear a watch, but still use my phone's stopwatch to keep time during a talk. I find that looking at a stopwatch during a presentation requires less m

I normally wear a watch, but still use my phone's stopwatch to keep time during a talk. I find that looking at a stopwatch during a presentation requires less mental distraction than: (i) keeping track of the time at which my talk started (I am talking about conference talks where the talks usually start a few minutes later than the scheduled time), (ii) looking at the current time and calculating how much time is remaining (it usually takes less than a second, but it is more time consuming that a tap on my phone). The trick is to disable your phone's auto lock, open the stop watch and run it. That way, you can just tap the screen (I am assuming iphone like smart phone) to see the current time. I think this can be done as discreetly as checking my watch. The biggest advantage of using a stopwatch is that it provides evidence of how long you have been speaking for. I have had cases where the previous speaker overshot his/her time and a session chair tried to get back on time by cutting time from my talk. In such cases, I have had to point to my stopwatch to say that I still have more than five minutes left. (Usually the talks are twenty minutes, so having five less minutes is a big deal). This (a session chair punishing me for the previous speaker's tardiness) has happened twice to me in the last year.