Why integ testing always run in one region?

[zorrofox]

According to the Running large numbers of Tests we can run parallel regions in several regions at once and even we don't specify any regions the yarn integ-runner will default running across us-east-1, us-east-2, & us-west-2. But when I run the command yarn integ-runner only one region will be tested and if I don't specify any region it will run on us-east-1.

[pahud]

It would spread failed tests into multiple regions to run in parallel like this.