I have been redirected from the main checkpoint to these lanes a couple times in the past. I don't think there is a very well-defined pattern for the opening of these lanes though, since I have seen them open when there's no line at the main checkpoint, and I have seen them closed when there are insane lines at the main checkpoint.

On another issue, I noticed that the bus between the main terminal and siberia runs every 30 minutes. I was wondering if this is a hard rule or if it is just 'recommended' to go to the bus gate 30 minutes in advance. I have never used the bus, but I thought it would be a viable option to go through main terminal or siberia security and then transfer in case of a rush.

Edited to say: I only saw the sign about the 30 min running interval. I'd never used the bus myself, so go with whatever Blumie says.