But let's look at the rated cycles of said battery. It's 300. So if you ran it on battery power daily, charged at night you could wear it out since Jan 2014.

For me the rule is ABC. Always Be Charging so the battery stays topped up and not being used.

At the office we've had laptops sitting on desks for years that we pull off and find batteries in great shape with all having more than 50% capacity.