We are of course straying from the original question of the utility/relevance of pyrotechnics, and other ways to seek help. I tend to think of flares as being most useful for close quarters where there are other vessels able to assist - sometimes just to show which of the yachts out here radio'd a Mayday. But I don't like them. David raised the point that a fire extinguisher is sensible - too right; fire is a real concern onboard. And the thought of a drawer-full of flares going up isn't pretty.
[I feel I'm more likely to want to abandon ship because of fire than because of sinking. But I can't justify that feeling]
But back off-topic. I recall the story of the usefulness of audio signalling equipment in Kincardine, Ontario, on the Great Lakes. The story goes that in 1856 on a cold October day, a small ship left the Port of Goderich bound for Kincardine with Donald Sinclair and his immigrant Scottish family aboard. As the ship approached Point Clark, the sky turned black and a strong breeze started to blow out of the west, churning up the waters of Lake Huron. Late afternoon turned to dusk as the vessel slowly made its way north along the shore, and the captain began to fear that he would not make Kincardine before nightfall.
Concerned for his family, Donald Sinclair retired to the ship’s hold, prayed for safe passage, and then retrieved his bagpipes and started to play a lament. The heavy drone of the pipes along with their sharp melody drifted across the waters to Kincardine and prompted a fellow Scotsman to join in the lament. Hearing the second piper, the captain was certain he was nearing Kincardine and was able to safely follow the sound into the harbour. For many years after his family’s safe voyage, Donald Sinclair could be found at dusk at the harbour, where he would be piping down the sun in honor of the Phantom Piper who had saved his family.
source: https://www.lighthousefriends.com/light.asp?ID=1046