Google "battery conditioning" ... the Li-ion or Li-poly cells in your laptop are the same technology as those in smartphones and tablets (and don't buy into the hype, these batteries have been using the same chemistry for decades, they're constantly improving in small "evolutionary" increments but there hasn't been anything "revolutionary" about them for a long time).
Missing out on the initial "conditioning" cycles isn't critical, you can always "recondition" the batteries later. These batteries don't have the controversial "memory effect" which were thought to affect earlier battery technologies, these days the "conditioning" is probably more to calibrate the battery regulator chips and software with a 100% reference baseline.
Short version is that if you are always conscious of your battery charge/discharge and you rigidly adhere to best-possible patterns then you can extend battery service life to about 3 years, maybe even 5-7 years or longer ... while if you rigidly adhere to the worst-possible practices then you can shorten their service life to 6-12 months.
- always try to charge batteries to full 100% instead of little opportunistic increments wherever and whenever you can find a plug,
- avoid charging and discharging the batteries simultaneously (that is, avoid using your machine on external power when the battery is dead) because that exposes the batteries to heat-accelerated aging which will degrades their chemistry and reduces their capacities,
- avoid storing the batteries (and laptop) unused for long periods of time, it's best to periodically top them off then use them a bit then let them sit another few weeks in a partially-charged state (say 25% to 75% total capacity).
You'll find plenty of opinions and arguments and personal anecdotes about what works and what doesn't work in the care and treatment of your batteries. I tend to put more weight onto sources who consistently get long battery lives from their tech (3-5+ years) and less weight on those who've never done any systematic side-by-side controlled experiments/testing. When all else fails, the advice of the battery manufacturer (and smart battery engineers) has precedence in this area over the advice of the general public.
I usually always plug in the charger whenever use the laptop. when it reach full 100%, I don't unplug the charger. I only unplug it when turning off the laptop. I'm sure modern laptop has auto cut-off feature.
Li-Ion batteries will last a bit longer when not kept at full charge, especially when stored. That's why that setting is there. However most users will find the life of the battery exceeds the useful life of a laptop anyway. After a few years the hardware becomes so outdated that most people replace the whole machine before the battery gives out. So for most people it's better to have a full charge ready to go but it depends on your pattern of usage.