[hakejpc]

The reading I did years ago stressed that you should definitely cycle batteries to as close as Zero as possible, but if you want to do long-term storage keep them at 40%. Seems like there is a lot of myth around how batteries work and proper practice. A unified resource on this would be great!

[aeternum]

Depends on the battery chemistry. NiCd and NiMh batteries which were very popular 10+ years ago do have a memory effect: https://en.wikipedia.org/wiki/Memory_effect

LiPo batteries do not have a memory effect, and you should avoid deep discharges.

[StreamBright]

I think the linked study gives you some insight. The problem is that we need all the capacity we get using a mobile phone for example. You can't really have a 2x capacity battery just for the ideal life time unfortunately.