For the trio of Farber/Brigham/Children's, it works extraordinarily well and reflects that they are all very practically interconnected - since Farber doesn't (currently) have their own clinical staff, you have pediatric cancer patients and practitioners flowing back and forth to BCH and the same thing for the Farber clinical beds located in Brigham. From the cancer angle, they all kind of function as one hospital.
I know from an urbanism perspective, gerbil tubes are frowned upon, but for this neighborhood it really does make sense. Besides the legal and environmental exposure angle for patients, and convenience for physicians, it is fantastic for staff transferring equipment and samples (clinical or research) vs. trying to navigate curb cuts and stoplights. If you could get a direct connection to a hospital lobby from a T station, now that would really be something. The sheer number of people and vehicles (including ambulances) have made the whole street level a total mess for decades, particularly around rush hours.