It is really worth paying attention to when the Extra Magic Hours are happening, and for which park, as this can make a big difference to crowd levels at a particular park.
Extra Magic Hours are when one of the parks either opens early or closes later, these hours can only be used guests with a valid resort ID.
If you are staying at a Disney Resort then the Extra Magic Hours can give you the opportunity to experience some of your favourite parts of a park before it opens to the public or after it has closed to the public.
If you are not staying at a Disney resort then it can be beneficial to avoid a park that has Extra Magic Hours as they tend to be slightly busier on those days.
See ya real soon!