While not a direct response to the two-lane idea, if you're interested in exploring these processes in general, searching for "design process" will get you a to

While not a direct response to the two-lane idea, if you're interested in exploring these processes in general, searching for "design process" will get you a ton of info. In much of the design world, though especially in UX, design process navel gazing is somewhat akin to tech stack navel gazing among web developers.