What Use Is An F-call?

What use is an F-call? I've been participating in contests for a little while now, both as part of a club, using a club station and equipment and under my own callsign using my own radio. When I did my first contest as VK6FLAB with 5 Watts, it was to see what effect it would have on my experience. That was over a year ago and during that contest I made many contacts and had lots of fun. I must confess that in the back of my mind it niggled a little that many of those contacts were on UHF and VHF, rather than on HF. Recently I did another contest using only 5 Watts, this time all my contacts were on HF only. I was on air for about 7 hours and made 39 contacts with 29 stations around the globe. I didn't quite make it half way around the planet, but 16700km goes a long way. For my contact, it was from Perth to Austin, Texas, about the same distance as between London and Sydney. It didn't sink in until recently that this means that with my radio, using 5 Watts, I could talk to most of the world with a littl