Riding fixed gear is like driving without brake lights

Have you ever ridden in a fast, close chain gang? My experience is that you pedal hell for leather most of the time, then cover your brakes as soon as you spot any freewheeling ahead of you. I think that, if riding fixed in this context, you should be thinking about calling "slowing" in cases where normally you would expect the act of freewheeling to suffice.

That's where you're doing it totally wrong. You should never have to brake in a chaingang unless you're actually stopping or the whole group is slowing down. Same as when you're driving on the motorway, if everyone thinks in advance and doesn't react suddenly to everything that happens or might happen then it'd all go swimmingly. obviously if the person in front jams the brakes and you're behind you're going to need to hit the brakes yourself. But if you're 4 riders back then you need to start slowing when the first person has hit the brakes otherwise the concertina effect only gets worse as the number of riders increase.