Yep, we do. It is part of the process just like testing. For the most part, it is not painful - most features are variations on existing patterns, and don't need updates. When we do code up a new pattern, we update docs.

And you are correct - we use consultants on the team, and hire in gig workers for small tasks on a regular basis. When I worked on a small core team without much churn, I did not do any of this.