In all I’ve snugged up the steering boxes on two or three of our 1970’s Volvos and a 1966 Jeep pickup. Can’t say there was much of a scientific approach used. In all cases it helped reduce the play although I was reluctant to screw the adjuster in very far. From what I’ve read about it, and it makes sense to me, is that the gears wear out the worst where the steering wheel is dead center at 12:00. So if you tighten the screw to where there is no play at 12:00 it can be too tight and cause binding when you turn the wheel off center to the left or right.

As I recall I probably ran the screw in in about 1/4 turn increments, tightening the lock nut and test driving between each adjustment.