As reported in Edge Magazine, the 4 hour map rotation period for both Turf War and Ranked Battle’s in Splatoon has now been cut in half to only 2 hours in Splatoon 2.
Here is the quote provided by Splatoon 2’s producer Hisashi Nogami:
“We feel that part of the gameplay is actually selecting which weapons would be best for that combination of two maps. In Splatoon 2, the maps rotate every two hours, so it’ll be a much faster cycle than the previous game.” Source
Splatoon 2 Launches on Nintendo Switch on July 21st.