In my previous company, there was a big focus on creating and maintaining documentation around the code, MAINTAINING specifically. It takes enormous amount of time and resources. And yet, it would take a few senior developers or, again, huge amount of time to understand the code. In my current company, mostly what we use is architectural diagrams. There is no time required to create these diagrams, done automatically within seconds. These diagrams updated automatically based on code changes. That takes minimal amount of time to create and maintain technical documentation.
I guess the question is would you prefer pages of written documentation (which most likely is outdated) or software architectural diagrams which you can navigate through. Each object on the diagram is clickable which allows you to drill down to the next level if needed?