Your information source is not correctly state the real truth.
It is written on Li-ion battery of laptop that you need to fully discharge and charge a battery several times to let the charger fully calibrate the battery.
Li-ion battery has complicated charger and monitor inside. In order to calibrate, a battery need to be fully discharged. However, it would not hurt to have charger always on. At least that is what a good charger will do. I happened to be in a company that makes good battery charger.