The 18ft pole has a closed length of 4' 9", which is the same as the closed length of the 22ft version. Technically you add section from the longer poles - the 25ft, 30ft and 35ft. These poles are 5' 5" long when closed. You would not end up with a 35ft pole though as your first 4 sections are from the shorter range, it would be about 31ft.
Ideally you would also need to remove the base insulated section (with no overlap markers) before adding extra section.