Ok..so let me dig this ditch a little deeper. While I understand the logic, what I don't understand is the technical. How do all three fasteners play a role in setting and maintaining the proper tension on the p/s belt?

 

I don’t know where your location is but up here in New England, especially with my twin inboard boat I would have squealing belts come springtime. The boat would lay up in my yard for winter and the cold would contract the belts tight against the pulleys and stretch them out. And quite a bit too. Solution was after winterizing the engines in the fall, loosen the belts during layup. Of course this is a moot point if your garage is heated or your in warm climates

 

I think the confusion is in AC cars where alternator and power steering pump is on the same side of the engine. In that case you have to tighten the one with two belts, before the other one (only getting one dedicated belt tight) then adjust the one with one belt, which will tighten it around both.

As far as tightening the three bolts on the power steering pump, the most important one to tighten first is the one in the adjusting slot. However in some cases the power steering pump could be at an angle and tightening the other bolts will straighten it out, thus either making the belt loose or too tight.