When working on a face you can fast forward time, and that's useful. However, if you need to test things at specific times, for example including complex calculations, then it's pretty difficult to do so.
I agree. I am currently trying to implement adaptive lume on a watch so that parts of the watch only line between sunset and sunrise. Being able to take the current Tim in the app would really help when testing as currently I need to wait for sunset etc to see if my code had worked.