A lot of work for something that's unnecessary, in my experience. Factory chargers are "smart" in that they cut current to the battery when appropriate. I've always charged batteries when they need to be charged, and left them as fully charged as the charger said they should be (assuming you're using authentic Milwaukee batteries and chargers; if using 3rd party stuff, all bets are off). Charge and discharge cycles are what wear down batteries in my experience, not storing them at high states of charge. I know its anecdotal, but I've never had a battery go bad on me doing this. I've actually got some lithium ion batteries that are over 15 years old and still function and hold a charge as good as the day I bought them. I've seen this advice several times on this forum, and it usually leads back to the internet's favorite battery reference, battery university. There's a few articles on there that contain some pretty questionable assumptions and studies/citations as their source. I'm more than happy to trust Milwaukee's instructions on how to best use and care for the products they sell, and it hasn't let me down yet.
I agree with you on the chargers, and doubly on third-party chargers.
But as a guy who works in the tech industry and has spent a lot of time in my job talking to engineers who work exclusively on batteries, I can tell you that you're incorrect and correct at the same time. There is additional capacity built in that ensures you're never truly charging to 100% of the actual/full battery capacity (at least at first), but there is still economy in keeping the batteries from charging to "full" and additional (though less) in not leaving them in a highly-charged state. Another way to keep your batteries running long is to avoid "topping them off" by charging from three bars back to full. Run 'em down to one bar (but not dead) and then charge them up (preferably to 80%). Rapid charging actually doesn't put a lot of extra wear on the batteries...until you do it at over 80% or so of charge. Then it puts a lot of wear and year.
The extra capacity thing is done as much as anything to keep their warranty costs low (and the math in the percentage points adds up pretty fast when it comes to battery warranties), but it's an approach that works. And it's built-in headroom for a strategy that is essentially the same as "not above 80%", though I doubt they're building in that much extra capacity (which is why you still have opportunity to benefit - charging from 40% to 80% is very low wear on the battery).
I don't tend to over-do this approach with my Milwaukee batteries, and I'm not suggesting you're ruining your batteries if you don't. I do it if I have the time and thought to it, which is most of the time. I don't worry about it too much one way or another, though my batteries do last a long time.
It's been more important with my cell phones - those are generally hard/expensive to replace - and I'm a little more diligent about it there. I have an app called Accubattery that reminds me to remove my phone from the charger at 80%. Two years later I still have 91% of the original capacity.
I think a lot of us are awash in batteries, so they're not getting that many cycles to begin with. I'd be interested in knowing what their design spec is for charging cycles is...
Anyway...
