typically a battery should hold its full charge for quite a long time. Weeks, maybe more. However certain factors will determine a battery's holding ability: How many times it's been charged/drained/charged (cycled): The storage temperatures; slow failures. You know how they say "put your C and D and 9volt batteries in the freezer to keep them fresh" ? This is a common myth. The extreme temperatures actually will cause them to discharge while inactive over time. Does your car battery ever get drained in the winter over really cold nights? Batteries should be stored at manufacturer specific temperature ranges.
(BTW: I have a friend that works for EverReady Battery Company)
When I first get my Leo battery I charge it up for probably 20 minutes until fully charged and the light goes off. It's lost that much charge sitting on a shelf, being shipped, etc. Most all my Leo batteries last about 9 hours the first day, give or take. I use them until they are fully drained blinking to be charged. I put them on the charger over night and take them off in the morning. Each day I use them they seem to last more and more. As of now I have one black Leo that lasts me about 17 hours (today from 6am til 11:30pm). This battery is about a month old. I alternate between it and my pass through so it gets used about every other day. It has a 3.0 Ohm Leo atty on it.
My pass through Leo is about a month old also, and lasts me about 12-14 hours. It has a 3.0 Ohm atty.
I have my original red Leo that has an black atty I bought from Litecigusa, that seems to burn really hot. I'd swear it is an LR (I still have to test it). That battery lasts me about 9 hours. It is my first Leo battery that I received early October and only a week ago put the black atty on it. The original gold atty for that Leo was a cooler vape and the battery lasted me about 14 or more hours then, but I lost that gold atty. It's probably somewhere in the house here. (I have e-cig parts on every floor).
So I'm thinking the Leo batteries probably have a bell curve of performance. The beginning peak at 2-4 weeks lasting upwards of 15+ hours. I've not seen the end of a peak yet, and one of my Leos is 2-3 months old.
My wife is using it now and it's lasted her up to 2 days! But, she vapes much less than I. I just bought her a second red Leo to use while the first is charging. I'll keep an eye on it but it's hard to tell with her how long a battery lasts. She can make a 380mAh KR808D-1 battery last for 2 days.
My wife had one atty break on her. She must have dropped it. It broke off at the threads. I know she left it at the theater she works one night. Found it the next day when she returned. Anyone could have messed with it, dropped it, whatever. It was that night she came home and noticed the atty was broke.
I lost one atty somewhere in the house, broke one atty at the threads. I've dropped mine many times on concrete, gravel, tile floors, etc. One has a slight nick in the paint. The rest are unmarred.