Three things: 1) These batteries periodically need to be fully drained and charged for whatever reasons (battery memory effect? calibration?), 2) Heat is an enemy to electronics, including the battery. Batteries spending long periods of time on charge are dealing with heat buildup - I would not recommend fully draining and charging on a regular basis for this reason, 3) Another enemy to batteries is leaving them uncharged for long periods of time.
All good points. Ive been pretty happy with my battery performance on my iPad 2. I will stick with the once a month drain and charge and otherwise just charge it when it gets to like 30% or so. Seems to be working good for us. Obviously, its hard to say long-term what this all means. Guess we'll find out in a few years.