Oh bbarn, if production aircraft don't use vortex generators, than B-52 A through E models never existed. There were long rows do v/g on the back of each wing ahead of the ailerons to promote better airflow to them. Boeing made around 500 or so of them. On the G and H models, ailerons were eliminated and roll control was done by spoiler action. I worked flight test for several of the large aircraft manufacturers and many of their aircraft used vortex generators. One funny thing we used to do to new airman just out of tech school was to send them to the tool crib for a special voltmeter to check the vortex generators. It never failed to amuse us and make the tool crib attendant unhappy when the kid went over there dutifully intending to get that special meter. In flight test we often tufted a surface to record laminar airflow. Depending on the camera results, we might add a row of vortex generators to see if airflow to the surface was improved and how much. If it worked out, than production was notified and a modification was authorized. Depending on the shape of a vehicle on the ground or in the air, vortex generators may be great or something to bang into tear up your body or really add to stability, but is all case by case as I see it?
I would agree with your case by case assessment. VG's do exist on many aircraft, there are even aircraft that have been issued a certificate of waiver for their use. Back in the 90's we looked at putting them on our Navajo Chieftain. They did increase payload and reduce fuel burn so I would say they do work - of course I never said they didn't either.
GENERALLY, they are not installed onto GA aircraft at the factory. Some of it is cost, some of it is paperwork, some of it is they aren't effective for a particular model. On a B52, I could see them as highly beneficial. A B52 has a specific mission and that has to do with carrying weight. A VG CAN lower the stall speed as well as increase lifting capacity. On the B52 I would imagine that the VG's installed on both the wing and the ailerons were never at the trailing edge of the structure but rather at or forward of the recovery point of the wing.
You will also find VG's on production aircraft in specific locations, not strewn out in a line on the wing. They are judiciously placed on various areas of the fuselage other areas to correct or control specific areas of concern.
Keep in mind when I see the term VG I immediately think of the early applications in the general aviation market. These devices were installed in-line on each wing at the point of recovery along the entire length of the wing. The purpose of those was to promote particular characteristics of a wing within a give flight envelope. I am not counting the ones installed on the nose of an Super MD-88 that control the airflow into the engines 100' behind them. That is a particular application designed to shape a small segment of airflow and not induce lift/drag properties on a wing shape.
I could certainly see them in the pictures earlier in the thread having some influence on the pilot chute. Would be interesting to see video of deployment both with and without them and how much effect they may have.
Here are two examples of their employment that I am referring to. Notice they are installed in a line and in front of the recovery point of the wing. Their purpose here is to promote laminar flow. By that definition if you install them on the trailing edge of the wing they cannot promote laminar flow as there is nothing to attach the air too.
I'll add this picture too. This is a flap on a Malibu, you can see they installed them forward of the recovery point. Again, their intended/purported use is to promote laminar flow so location, location, location!! lol