Read post #498 here again. The important concepts are there.
If you discharge them at a high rate, they terminate sooner and bounce back higher. You really don’t know what the capacity is for sure. The older, more abused the cells with higher internal resistance makes the problem worse. The voltage simply sags and the discharge terminates. That’s one way of knowing the cells is on it’s way out > no voltage support.
Similar thing if you charge them at a high rate to storage, though not nearly as pronounced as the charger ‘ramps down’.
Storage is ‘approximate’. 3.7v is not a magic number. Anything from 3.6-3.9 will work, especially for relatively short term storage. For really long term shoot for 3.7v, done at a low rate (charge or discharge), then put them in a Ziploc and in the fridge, minimally avoiding higher temperatures at least. High temp + full voltage is the worst scenario.