1. The host city gets it for 40 years, to amortize the cost of building the facilities and to improve through experience.
2. Distribute groups of sports (skiing events, swimming events, etc) to different host cities, to reduce the impact on each city and to foster a sense of international cooperation.
3. Stagger the events throughout the year, to avoid scheduling conflicts and viewer burnout.
https://invisiblesummer.net/2012/08/12/towards-a-distributed...
Summary:
1. The host city gets it for 40 years, to amortize the cost of building the facilities and to improve through experience.
2. Distribute groups of sports (skiing events, swimming events, etc) to different host cities, to reduce the impact on each city and to foster a sense of international cooperation.
3. Stagger the events throughout the year, to avoid scheduling conflicts and viewer burnout.