I have no idea how a "middle-of-the-pack quality" standard battery would perform in Walmart testing because I don't know their test sequence and I have been using high-quality AGM batteries for many years to minimize the inconvenience of frequent replacement (and dealing with prorated warranties). I could have received free replacements from Nissan for the original batteries in the 2011 and 2015, but chose to replace them with deep cycle AGM batteries to minimize the risk of corrosion under the hood and avoid the inconvenience of premature failure.
Edited to add:
You can get an inexpensive battery tester from an auto parts store or Harbor Freight that will put a load on the battery and give a good test. Here is a photo of the Harbor Freight tester I purchased a while back on sale. It is a voltmeter with a resistor load that can be momentarily connected (don't exceed 15 seconds to avoid overheating the resistor). It put a load of about 80 amperes on my battery and the voltage under load stayed above 10 so my 15-month old OEM battery is in better condition than I expected.
Edited to add:
You can get an inexpensive battery tester from an auto parts store or Harbor Freight that will put a load on the battery and give a good test. Here is a photo of the Harbor Freight tester I purchased a while back on sale. It is a voltmeter with a resistor load that can be momentarily connected (don't exceed 15 seconds to avoid overheating the resistor). It put a load of about 80 amperes on my battery and the voltage under load stayed above 10 so my 15-month old OEM battery is in better condition than I expected.