I have used one routinely for years in sunny southern Arizona to pinpoint my location for the benefit of other SAR teams and the helicopters supporting us. I may have mentioned in other posts about showing my location to a helo before it even took off (it was about 15 miles away). Dur the time I was active, there was at least one instance of a party needing assistance who effectively used a signal mirror to gain attention.

Actually there are many effective ways of attracting attention to helos and other aircraft. Your techniques are quite effective and will serve you well, but the aircraft needs to be fairly close. The advantage of a signal mirror is its ability to attract attention at a distance. There are cases of planes responding to a flash where the signalling party did not even see the place.

Our group ran some controlled tests on the utility of signalling (waving arms, jumping up and down versus immobility) and it makes a significant difference if you do something - almost any action will improve your chances of being spotted.

On one very memorable occasion, we ran into a climbing accident while out for fun, not SAR. We had to build a fire because when the helo came, it was night. Signal mirrors don't work too well then. Fires do indeed work 24/7.

I was out doing archaeology just last week and I used my "signal mirror" (the shiny surface on my compass) to show other members of the team my location - significant because I had the wheels to return them to camp (and the waiting cold ones). I always have either my compass or a dedicated signal mirror, or both, with me. In my old age, I am trying to set a shining example.