This ship that the adeptus mechanicus keep on rotating station near the warp gate, How does it not get shredded by the well of night

As I understand it, it doesn't avoid it.

The Mechanicus picket, which is of cruiser displacement, gets switched in and out after 6 months of duty and I also believe that not ship has lasted the whole 6 months before needing to put in for refit and repair.

-Durandal