A wise man (David Hepworth) once said that you are always 25% worse than you think you are and your competition are always 25% better than you think they are. He was talking about magazines but I reckon you can apply that rule to just about anything you want. For example, at the end of the month I always have 25% less money in the bank than I think I have. Painting the living room always takes about 25% longer than you think it will. And… clearing one small allotment of couch grass infested manure takes roughly 25% more wheelbarrow loads to shift than you think it will. The under-gardener will get 25% more filthy than he anticipated and he’ll probably be 25% more knackered than he ought to be.