Yes, counting metronome beats...if there are many... one can lose count, especially me as my mind will start to drift thinking about stuff...so to keep track of minutes, I have at times scratched marks in the ground indicating minutes...If exposures are longer than 5 minutes, I'll use the stopwatch mode. When I've forgotten my stopwatch at home, my phone's timer will suffice. I love my little phone, as I can take a shot of the scene, make notes, and have film data stored in it (filter factors, reciprocity, etc). Beats fumbling around with paper...which I have with me just incase the phone goes kaput.