The recommendation about "full charge, full discharge" is really based on the old Nickel Cadmium (NiCd) batteries, which could develop a "memory effect" and apparently reduced capacity if you didn't follow that advice. I have a rechargeable electric shaver with this problem: when the battery drops to about 80%, there's a sudden voltage drop, and the shaver thinks the battery is flat. If I put it in the charger for 1 second, the "flat" flag is reset and I can use it for weeks more.
The Lithium Ion batteries in laptops etc are different. They can be permanently damaged if they undergo a deep discharge, so the charging circuits in e.g, laptops do not allow that. Heat is a major factor in the life of a Li-Ion battery: they all degrade over time, more so if used in hot conditions, such as in a laptop that is always plugged in. That's why you ought to remove the battery if you always use a laptop on AC. You can even put the battery in the fridge.
