You only want to “Update Frames” for a view when it has all of the constraints it needs. For example, if you have a view and it has a top, bottom, leading, and trailing constraint, then it almost certainly has enough information to determine the frame, so “Updating Frames” will make sure that the view is not misplaced. On the other hand, if you have a view and just add a top constraint, the view doesn’t have enough information to determine its frame, so “Updating Frames” will not work (it doesn’t know where the view should go).
In general, “Update Frames” when a view is misplaced (you’ll get a warning in Interface Builder if a view is misplaced). Knowing when you can use “Update Frames for Items of New Constraints / All Frames in Container,” just like with all of Auto Layout, just takes practice and experience.