Right, I would think a digital watch would be more obvious, especially the paper and pen you use to record the time.
I find a cell to be more discrete and silent. Between a screen shot to record the time, GV, and the stop watch, it's a win-win all the way around.
I also work with ACL. I haven't seen the cell restriction in the shops that I do.
"I told myself to quit you; but I don't listen to drunks." -Chris Stapleton