> I remember watching a design documentary years ago
Was it Map Men? They mention not forcing the London tube map onto the geographical map. It has two parts:
1. "The Tube Map nearly looked very different" https://www.youtube.com/watch?v=cTLCfl01zuE
2. "What went wrong with the Tube Map?" https://www.youtube.com/watch?v=jaEhvWXmLyk