ya know those tests, I am not sure what to say about them as I have seen a batter get trickle charged and thrown on the tester to show its good. I then took it home, did not hook it up and thought I would throw my meter on it just to be sure I wasn't wasting my time. 2 hrs after the test showing good, nothing being hooked up to it, the battery now was down too 11.3 volts. Went back an hour later with still nothing on it and now its showed 10.5. By morning it was dead. I took it back as it was under warranty and they did the same exact process of just leaving it unhooked next too the tester for 2 hrs after it passed and it also showed it was loosing voltage hours later.
You really only need too slightly damage one of the cells in a battery to have it do enough damage to say its only going too last a few more months. Problem there is that until it gets too the point I just described we can't see that anything is wrong with it. So I guess I would say that load testing it can't hurt anything, but also isn't the final word on the subj. Testing the alt also can't hurt and I am sure I tell people to clean the connection a lot more then its really done. It took me seeing that it only takes a slightly loose connection on a battery to cause a problem to develop over months. think most people just don't understand how important keeping the contact area of the battery clean is. Heck I am surprised when I see the average DIY'er has tapped a ground screw into the chassis and scraped the paint off...