Listen, I'm high, tired, and didn't even slightly read the underlying study. But, wasn't that the whole point? That they tried maximizing the rate of delivery to the affected area, and that it seems to improve the ratio of therapeutic benefit to harmful side effect?

Spitballing wildly, I'd imagine there's some sort of optimal rate for tumor destruction (obviously dependent on the type of tumor and other specific details), and optimal rates for non-tumor preservation, and you'd be able to optimize between the two by utilizing multiple beams from multiple directions in certain scenarios.