@FAST6191 Great writeup!
Just a few corrections:
i) Are you sure about that? I never checked but I think it's the exact oppsite: Not sitting in a charging stand draws power as the gamepad constantinuously checks if the Wii U has been turned on. When fully charged in a stand the power for this checks should be taken from the stand, not from the battery. So sitting in a stand while not used for a longer time should be better to prevent deep discharge.
ii) AFAIK all batteries (except maybe cheap china ones) are overprovisioned anway. So when the device shows 100% charge it's really ~80%. Also best capacity for storing batteries for a longer time without beeing used (so out of the gamepad) is 40%. Buy a brand new battery and (actuall don't do this except for reseach purpuses) use it without charging: It should be at around 40%. The manufactureres precharge to this for a reason.
"doing full charge cycles in general is going to have more of a deleterious effect" is new to me. Could you explain this, please?
There's no guess: Lithium charging rule of thumb: Start fast, go slower at around 80% (I love how you already told that in your writeup)... Go slower the more you go to 100%... When you reach 100% do drop-charging (which means to only charge a tiiiiny bit when the battery looses charge even while not used). Wait, you're right: There is a guess: My question from i.
The thing is: The gamepad is always on. Again: "the gamepad constantinuously checks if the Wii U has been turned on". The faster charging algorythm below 80% might draw more power than drop charging, so leaving it in the stand might really save power.