If you can immediately buy and sell between exchanges it should quickly level the prices. Something like that is easy to automate, so any slight margin that appears will be almost instantly leveled.
The difficult part is in transferring non-bitcoin currency to and from the exchanges.
If you for example buy bitcoin in the US and sell in China, then you end up with a surplus of CNY on a Chinese exchange's account. Getting this converted and transferred back to the US will incur exchange and transfer fees. The transfers might also take weeks - which will limit you to cycling small amounts of money slowly, or risking a lot of money at once if the exchange "has banking issues".
In the end, even a 5% or 10% price difference might not be worth running the arbitrage cycle on difficult to deal with exchanges in strange countries.