Some time ago, I stumbled upon a graph (sorry unable to retrieve its URL) showing correlation between the discharge depth of a battery and its lifetime in cycles.

Obviously, the less you discharge it, the longer it'll last. OTOH, the less you discharge it, the more you'll cycle it.

From data scraped from the graph, despite all of this is not linear, I found the best compromise was to not go lower than 50 % discharge.

I've been applying this discipline to my new notebook battery for 6 months and its full capacity is now at 95 % after almost daily use. And 3% on the lost 5% were after I ONLY ONCE let it go to full discharge.