Unless you have something extreme like a car sitting super high in the rear and driving it compresses things alot. Less than 1/2 will work.

When the front leaf spring is parallel with the rocker panels. This is just about as forward as the yoke will ever be. Now lift the car by the frame and allow the springs hang until the shock absorbers reach their limit. Not many circumstances will allow the yoke to go in further than that.

I had a leaf sprung Dodge truck. With grease smeared on the yoke. I drove it, raced it, power shifted it, towed a trailer with it and found 1/4" of travel witness by the grease line.