When people make a princess cake, they get a recipe off the Internet and follow it as best they can. However, it's unlikely it will look exactly like the picture on the Internet. Why? Because of the individual's relative lack of concentration and skill compared to those of a professional baker. Provided that the instructions have been followed, however, the cake will be perfectly edible.
Chapter Five suggests we go at the programme hammer and tongs but then suggests we claim progress not perfection. How can these two ideas be reconciled?
We make a 100% effort, but because of a relative lack of concentration and skill, we will drift and make mistakes. Provided that, as soon as we realise we have drifted, we come back on beam, and as soon as we make a mistake, we fix it, as best we can, there is no harm done. The results won't be perfect, but they'll be perfectly 'edible'.