When designing a feature, an improvement, or a product i'm curious at what point would you refer to the user journey map? Why would you refer to it? and what information or insights would hope to gain?
Depends It's crucial to user Journey? You could use Agile UX and document lightly, if the new feature impact the user journey, or delivery a big value you should consider update your journey map.
When a crucial information in the Journey Map, you can remember, discuss, thinking, together with your team, understading how to improve this feature, how the user feel in this point.