If you have a lot of small classes (that are often created and destroyed), and they all depend on the settings, how would you do that?
It would be nice not to have to connect each one to some kind of "settings changed" signal, and even if I did, all the settings will be updated, even those objects whose settings didn't change.
When faced with that myself, I've found it's better to control the save/load settings from a central place. Do you really need to save/load the settings on a regular basis or can you have a master object (likely with a list of the sub-objects) control when savings actually need to be done? Or, worst case, as the objects are created and destroyed have them update an in-memory setting map in the parent collection and save when it thinks it should be saved, rather than child object destruction.