Right. That's still a thing that happens in series-wired batteries. Voltage depression of individual cells seems to correlate more with deep discharges of a b

Right. That's still a thing that happens in series-wired batteries. Voltage depression of individual cells seems to correlate more with deep discharges of a battery (perhaps combined with differences in cell quality within that battery) than anything else. And deep discharges were what people were deliberately doing to fend off the evil spirits of "memory effect" probably made the problem worse.