This link revealed that the title sequence animators are limited in the amount of time they have to animate an opening (the length of the opening song), and the places shown/amount of time it takes to move to each place depends on where the characters are on the map. Additionally, there are rules such as every opening sequence must show King's Landing, Winterfell, The Wall, and wherever Daenerys is.
As the title suggests, I was just wondering which episode's opening sequence shows the most number of locations in the 90 seconds that they have to work with.
Note, I chose "locations" in the title because as far as I can remember all the places shown were cities, but just in case there were any landmarks I wanted to allow them to be included.