Yeah chip efficiency. The amp load at 1.5ohm is at the maximum straining the circuitry to deliver the amps. 1.5@10w is 2.5 amps = 2.5 amp draw at the mods amp limit wit a single battery. 3.0 ohms @ 10w is only a 1.8 amp drain and easier for the circuitry to achieve.
I know there are some on here that try to claim differently and I know where you got that edyle, this is not a knock to you, I put this question to those individuals, but the fact is the output is either 2.5 amp drain or 1.8 amp drain both at 10w of heat/power which lasts longer. Which strains the chip more in efficiency? These are the two factors that play in double the run time.
Sorry, to the op it has more to do with gauge of wire. Heavier gauge can give a richer flavor with slightly more vapor at the same wattage. Due to surface area. At the *same exact* *wattage* thinner gauge will always heat faster.
Just hope this helps some people have a better experience with thier vape.
And let's compare apple to apples not a mech to a standard chipped vv, two different animals.
My 0.4ohm coil lasts all day, probaly about 12hrs on a 2600mah 18650
That's great it's working for you and that's the other End of the spectrum where it works. So strong you for have to chain vape it.

So if you take 200 puffs a day on it and I take 600 puffs a day on it the battery will last me 1/3 it lasts you. Or 4 hours.
If your interested in what I'm talking about great if not no big deal just as long as your vape does what you want.. Me I don't like changing bats all te time so I coil to give me the power and the life on the zmax chip.
vape on peeps!