once or twice a month a full battery drain and then a 100% charge helps increase the battery life
That is incorrect, a full discharge is never beneficial to LiON battery capacity. The battery life of a LiON battery is dependant mostly on temperature, discharge rate, and age. In fact, low charge state actually is harmful to LiON battery capacity; although modern batteries have circuits that tells the system to shutdown before it became really harmful to the battery, it is best for LiON battery to be plugged in as often as is convenient.
also gives more accurate battery readings.
As for calibrating battery meter by full discharge-recharge, that is partially true. Modern smart battery comes with a microchip to keep track of the state of charge. The following is a quote from HP regarding Smart Battery System in their laptops:
Repeated short discharges and recharges cause increasing inaccuracy between the state-of-charge of the battery and the Power Meter readings. Periodically, the battery needs to be calibrated to "relearn" its usable capacity so it can synchronize its charge status with the Power Meter. ... The user simply has to periodically discharge the battery until the 5% capacity alarm is received. The need to perform this procedure will vary with individual use. In general, a Li-Ion battery should be calibrated a minimum of once every 3 months. A battery that is seldom discharged completely should be calibrated about once a month.
and the following is from Battery University:
How often does a battery need calibrating? The answer depends on the application. For practical purposes, a calibration should be done once every three months or after 40 partial cycles. If the portable device applies a periodic deep discharge on its own, no additional calibration will be needed.
The need for calibration comes from the mismatch between the battery's chemistry and the microchip that estimates the battery's state of charge. This mismatch develops over numerous partial discharge, although unlike the memory effect in NiCad battery, it does not affect the battery's actual chemical capacity and is reversible by letting the battery relearn its bottom and top charge state. Do not do calibration too often since deep discharge does permanently harm LiON's actual capacity.