I'm not sure how I hadn't read this before, but if you're looking for a handy guide to content journey mapping, this is for you.

When we start working on an end-to-end service, we define the users, then map out the journey. This process shows us what tasks users need to complete and highlights where the content doesn’t help them to do this.

What follows is pretty much a step-by-step to get you started. Of course, you'll need to take your organisation's specific circumstances and constraints into account. But hopefully it should be easy to get the right people together and start mapping those content journeys. Also, you can do all this at the start of a content project, not just when things already exist and are ready for an update.