Except I always make sure they are fully topped off before doing runtimes...
Actually, since I can rely on power here, and if not here, there are 6 2,000kVA generators at work with fuel for a month, I tend to store most of my 18650's at 30-40% charge for longevity.
In the case of the Mags, life is waaaaaaay to short to do runtimes. Somewhere I have an LED dropin that will run for about four weeks on 2 8,000mAh Ds. The data-logging meter's battery won't....
It lasts about 72hr when data-logging. Need to build a 9V source that is very well regulated for that. Or build a silly battery pack for it.