question about mbp best battery practices
Recently I had my mbp ('11) serviced for a battery that had stopped retaining charge about 20 months after purchase. The battery had gone through about 40 charge-discharge cycles; my laptop spends most of its time in my office or at home so I use it mostly on AC power. The rep at the genius bar insisted that my battery failed because I didn't use it enough, and he said that the battery needed regular exercise to stay healthy. Since I had never heard of lithium polymer batteries breaking so early from underuse, I did some homework.
-Apple recommends (http://www.apple.com/batteries/notebooks.html) to use at least one charge-discharge cycle per month, and I certainly met that requirement. When I brought this up to the Genius, however, he said that guideline was too low, and recommended that I average around 300 cycles per year.
By the way, Apple covered the repair under warranty, so they seemed to think the battery was defective and didn't just die from normal use.
So my question is, did the rep know what he was talking about? Are there reasons why I need to cycle my battery anywhere near 300 times per year to keep it healthy? References would be greatly appreciated.