I guess that's why no one learns morse code. But I think that knowing how to SEND and RECOGNISE SOS ...---... is still valuable. It is an unmistakable signal and cannot easily be mistaken for any naturally occurring phenomenon.

Some lights have a built in strobe or SOS modes, which could be useful. Using a built in flash mode will generally prolong the battery life, so use it if you can.

If you have a simple on/off light, you can still flash it by turning it on/off, or by turning it on and then covering the lens with your hand to create a flash (unless you have a light with a built in signalling flash button). Another way is to rotate the light, like a light house, at a steady speed.

IMO a slow, steady paced flash (or an SOS) is easier for a searcher to recognise from a distance. If you flash too fast it tends to look like a steady light (from a distance).

SOS can be used with lights and sounds and even markings on the ground, so it is very versatile and is internationally recognised.