The Watchtower is God's Organization after all, so they won't really consider themselves to be testing the faith of others, rather, they are presenting new and refined truth, so the individual is responsible for their tested faith, and if they can't keep up with Jehovah's chariot that can move whichever way it chooses, well, that's on the individual. Casualties are never the fault of the Organization, it is a sifting out of those who don't belong in the first place.
One paragraph from a whole issue of garbage ...
*** w87 6/15 p. 20 par. 17 Testing and Sifting in Modern Times ***
Year after year Jehovah continues to refine and cleanse his people. Collectively, they have subjected themselves to the refining process as to their organization, activity, doctrine, and moral cleanness. But what about us individually? Through his organization Jehovah continues to dispense “solid food” for guidance that refines the heart. Our motives are tested and examined. (Hebrews 4:12; 5:14) By responding to the refining, cleansing process of the Great Refiner, we keep clean as we await “the coming of the great and fear-inspiring day of Jehovah.”—Malachi 4:5.