Lack of planning has nothing to do with “build it and they will come” — and everything to do with communicating with the customer to understand what would make them come and why. Beyond that, this is not about getting a percentage done, but 100% of the least viable amount of “done” complete that would result in a predefined behavior; spend money, use product everyday, etc.

Musician equivalent might be identifying few notable bands in a given genre and actually understanding which fans spend money, why, where they listen to it, what other music they listen to, how they discover new music, what songs they share with people, etc; never done music R&D, so honestly stretch, in part because I know distribution is way more important than the actual music, but that doesn’t change that ultimately it’s the fans listening to music that matter. The “build it and they will come” would be making full album with music videos before ever letting single fan or peer familiar with fan tastes listen to the music.