I think that it’s one of those dichotomies. One needs both a design and a prototype.
As you say, weeks of coding can save hours of planning. But weeks of planning can be wasted, too. It’s easy to write things on paper which don’t make sense or are impossible, e.g. ‘We will colour the unicorn fleet semi-sad.’ Ideally, the design and the prototype would evolve in concert, each iteration of one driving the next iteration of the other, spiralling like the double-helix of DNA.
The great virtue of a bias towards building prototypes is that at the end of a round of prototyping one actually has software which can do something — at the end of a round of design one doesn’t really have anything.
As you say, weeks of coding can save hours of planning. But weeks of planning can be wasted, too. It’s easy to write things on paper which don’t make sense or are impossible, e.g. ‘We will colour the unicorn fleet semi-sad.’ Ideally, the design and the prototype would evolve in concert, each iteration of one driving the next iteration of the other, spiralling like the double-helix of DNA.
The great virtue of a bias towards building prototypes is that at the end of a round of prototyping one actually has software which can do something — at the end of a round of design one doesn’t really have anything.