It just seems like there have been a lot more reports of short battery life in the past few years, and I don't know that anyone knows exactly why that is. I tend to wonder if it's related to the ever larger electrical load as Harley adds more and more electrical equipment, or is it just one more sign of the cheapening they have been doing with all sorts of components.
The tech gave you some good advice about the load test. While just cranking and observing the voltage isn't exactly the same as a real load test, it will tell you what you need to know. You don't want the bike to actually start when you're doing this, so make up a simple jumper to energize the starter solenoid switch with the ignition off. Connect a voltmeter across the battery terminals, crank the engine for 15 seconds with your jumper while observing the voltmeter reading. The voltage should not drop below 9.6 volts. That's the method I've been using for years, since I don't own a real load tester.
Some of us have had Harley batteries last more than six years, and some have had them fail in two or less. I don't have a clue how you can easily tell if yours is destined for early failure, but I don't usually recommend changing them strictly based on time in service. After deciding on a three year limit you could just as easily get one of those that only lasts two years, or you might be throwing away one of those destined to last six or more years. Doing a load test on a regular schedule might give you a clue about a slowly deteriorating battery if you follow the exact same protocol each time and record the exact voltage, but it won't necessarily help you predict those sudden failures caused by shorted cells or cell connector failures. In other words, there really isn't any foolproof method I'm aware of. Replacing them every year like we did back in the 60's might be an option, but with the prices of modern batteries it could get pretty expensive.
Jerry