Well, I have a failure to report. We can learn from our failures as well as our successes, right?

No emergency was involved, but I spotted my two companions about a quarter mile distant, hiking down a road to retrieve a vehicle and then come back to collect me when we had completed our tasks. The sun was at a perfect angle for signalling. I decided to try my compass mirror (Suunto MC-2), forming "V' with my fingers. I flashed and flashed without getting their attention.

Quite surprising really. Had this been an actual emergency,I would have dug into my gear a bit deeper and used my dedicated signal mirror.
Geezer in Chief