"Lifetime" is actually a pretty "soft" limit. Lithium ion batteries (actually, any battery) don't just "die" after they reach the magical number. It's a limit after which capacity drops perceptibly, i.e. anywhere between 75 and 90% of the original, specified one (varies from manufacturer to manufacturer).
Just FYI, batteries don't have an exact nominal capacity either. It varies up and down from 10-15% from one sample to another and from one batch to another.
Also FYI, Lithium Ion batteries have internal electronics that prevent them from ever discharging fully (because, unlike NiCd and NiMH, they don't have an internal electrochemical "safe-guard" that would prevent them from "discharging to death"), so a "full-charge cycle" is something you can't EVER reproduce on a consumer device. Unless you dismantle it, take the battery out, dismantle the cells and drain them with a resistor.
According to you, people should switch their devices (whatever they are) the moment they stop using them, and plug them in. My question is - what's the point of having a battery then? A simple capacitor would surely suffice
