The Commonwealth holds the Commonwealth Games every four years.
Once every four years.
Spain has a general election every four years.
The two major parties hold national conventions every four years, primarily for the purpose of nominating a candidate for President.
The Olympics are determined by the National Olympic Committee every year.
The f.I.f.A world cup is held once in every four years.
The scheduling of municipal elections depends on provincial or territorial law. Most cities and counties hold their elections at either fixed three- or four-year intervals. Saskatchewan's rural communities hold their elections every two years. Hamlets in the Northwest Territories also hold their elections every two years, while in Nunavut, the interval is just one year. See the related link below for more information.
Because it takes that long to get the venue ready and for participating countries to train their teams.
The Final Four is played at Lucas Oil Stadium in Indianapolis, IN every five years. It is a mandate because Indianapolis is the NCAA Headquarters. The other four years it is voted on which city should hold the Final Four.
A state law says it must hold the first primary
Presidential and vice presidential elections are both held at the same time, every four years. Since 1792, they are held the Tuesday between November 2 to November 8.
Christchurch hosted the Commonwealth Games in 1974.
Japan holds their elections every 4 years.