In reply to rginns:
They're for anyone who wants a bit of extra motivation to push themselves, to join in a social event, and maybe to compete against others too.
I did the Foundry one a couple of years ago, it was good fun. What I especially valued was the encouragement from the scoring system to try harder to flash problems (you get a sharp points decline for having to work something) - this taught me that I could hang on longer and fight harder than I thought.
I also burnt Seb Grieve off on one problem which was mildly amusing.