Yes, mogwai, I agree. Not only because of the Prize element (which doesn’t bother me, because I never enter and my dear brother gave me the book as a Christmas present anyway), but more because I would rather be faced with a proper challenge on a Saturday, when I have a bit more time, than on, say, a Wednesday, when, say, Vlad has to compete with all sorts of other demands and I can’t give him my undivided attention.
Of course others may be equally free or freer midweek than on a Saturday. But the continued existence of the Saturday Prize is surely a recognition that most people have more time on a Saturday than during the week, and so would relish a proper challenge.