battery lifespan doesnt decay so fast you know, you'd start noticing the decay at about a year with a mediocre handling, so a careful handling should leave you with a healthy battery for a longer period.
as far as i've heard of laptop batteries, people tend to ignore them and just use it as is, they don't even notice the damage they've done until years have passed.
at worst you'd lose like 10% of the current capacity per 2months, do note that its "current capacity" which means the decay lessens as the total capacity decreases, otherwise small capacity batteries made of the same battery type would lose all of it's charge in a few uses, but it doesn't.
although if i remember correctly the rate isnt by time, but by charge and discharge cycles.