Don't listen to people who tell you "it should last WAY longer than xx-hours"
Unless your battery is dying after 20 minutes of light use then I wouldn't worry. 1300mAh may sound like a lot, but it's not that much when talking about VV devices. The boost circuit draws a lot more power than you usually would, allowing you to use higher voltage.
I'm not sure exactly how your specific device's circuit board is set up, but odds are even when the selected output voltage on your VV device is at, or lower than the current voltage of the battery istelf, your still loosing power to the VV circuitry. In short, VV devices will consume more battery life for a given power output than a single voltage unregulated device.
Then take into account the million and one little variables like carto rez, how long you take a drag, how long you wait between drags, how much you actually vaped overall, voltage setting, coil design, device internal loss, etc etc and you will understand why it's nearly impossible to say "this battery should last this long" There is just no accurate way to do it.
Just as an example, I can burn through 18650 2000mAh AW IMRs in about half the time some people in this thread said their 1300mAh batteries lasted them. With certain juice, device, and vaping style my little 800mAh 18350s can literally last me all day. "Vaping time" is a horrible way to express any sort of information, because really no information is being expressed at all. Just a very personalized and specialized number that means almost nothing to everyone else.
I hope that didn't come off too much like a rant, and it wasn't directed at anyone, just a little commentary on something that I constantly see referenced in YT vids and on forums all over "vaping time' just doesn't stand up as any sort of legitimate factor, IMO of course.
What would be a more accurate way of measuring "vape time" would be recording the actual number of minutes the device is powered up under load. Basically add together every second that the carto is firing and that would give you a total "vape time"
Even that would still depend on settings, carto/atty design and resistance, but it would be far more accurate and universal, one person's results would actually be useful and able to translate to someone else.
If you think there is something seriously wrong with the battery, you could also do the math and see if the battery is lasting as long as it theoretically should. With the battery voltage, ohms of the carto, and capacity rating you could work backwards and calculate how many minutes/seconds the carto should be able to fire for before the battery reaches cutoff voltage, then attempt to keep a running count of actual vaping time and compare that to your calculated run time.
Although, this would be much more difficult to do with a VV device, the inefficiency of the design could throw your numbers off.