Does it make sense to leave the laptop on?

I replaced my PC with a laptop a few days ago that is plugged into two external monitors so it has to be plugged into the power cord. Now my question: how useful or stupid is it to leave it plugged in when I'm not using it and to what extent does it damage the battery?

You can do that, but the best thing to do is to remove the battery - then that's no problem.

So if you want to use a device in continuous operation, you should always make sure that the battery is replaceable when buying.

The ghosts argue. Some say there's no significant difference and others say the battery is older than it was when it was used. I have a 2 year old notebook that I only use very rarely and that I always have on power, so the battery health is around 90% for something.

It definitely makes sense to leave the laptop connected to the power supply, it does not damage the battery, it rather saves it. That the battery always remains full and that it runs in mains operation is better for him than if he would always lose a few percent and be charged again…

Yes, it is always good to leave the network operation inside
battery does not wear out or wears out less the performance is significantly increased no constant plugging in to charge and unplugging

This will damage the battery and ultimately rob you of its capacity. A battery should always be in motion and stay between 80 and 10%. If you leave it permanently infected, it will not move and will "rust" in the foreseeable future. To keep the battery fit, charge it when it is empty and remove it from the power supply. When the battery is down to 20 - at least 10%, then recharge.

If you don't want to use the battery, it would be better to take it out of the laptop for stationary use and only work with the power supply.