FatBoy - they normally go off all at once in your rucksack
How about 100 going off whilst you are driving - scared me nopeless last time !!!
Oh and one which switched off with a permanent beeeeeeeeeeeeeep - i didn’t have an Allen key with me to undo the battery and had to drive home for 30 mins with one stuffed inside a sleeping bag !!!!!
I think most people are clued up enough to leave extra time incase of delayed starts (at least I hope they are)