This question is answered differently by many people. However, if your laptop is stationary (always at your desk) then probably it makes sense to leave the laptop charging all the time. Research and studies show that frequent charging and discharging a laptop cause more strain to the battery and will reduce the batteries life span more than when it's plugged in throughout. I would clarify this by saying you should not leave your laptop charging all the time. This is because when you are using a laptop and it is on charging a lot of heat is generated which will definitely reduce the battery life. If you have a laptop with a Li-ion battery, then it is better to unplug your laptop when you are not using it. Lithium-ion batteries do not suffer from the memory effect, so there's no need to keep them constantly plugged in.