Timekeeping is definitely a problem. What with having to know when the MOPs are due to arrive & leave, when the archery competition is, when you need to start arming up, when muster is etc. etc. it's very difficult when you're not allowed a watch. It's an anachronistic chronometer. I just wear one anyway, making sure it's hidden under my sleeve, and I try to look at it discretely when I think MOPs aren't looking. It's a necessary evil, sadly, but without it I'd be pretty stuck, most likely tempted to carry my mobile phone around for the clock on that, which is even worse!
We could get announcements made over the PA but frankly I'd be highly likely to miss them. The PA seems to be in constant use commentating on the various arena displays, so I tend to switch it off in my head and not pay attention to it, otherwise I'd go mad listening to every word. Maybe a prominently displayed clock would be good or a canon-fire or something *shrug*.