You can do shorter than 2 years although 2 years with a years break clause is common. I'm on a 1 year lease and can jack it in after 6 months so it will all depend on what you landlord is happy with or what you want to pay per month. Obviously you can get a shorter lease if you are prepared to pay a little more per month or if the landlord needs a tenant sooner rather than later. And since Tung Chung is full of investor owned apartments it shouldn't be too difficult.