Ocassionally, I ask a heavy e-smoker, and a longtime customer, who has experience with these, to take a new model, and test it. I suggest they try to "kill it", so they can really see what it does. I give them specific instructions, like times on the battery, Charging times, flavor, etc.

Here's one on the T-rex.

Did not precharge the battery.  The instruction manual did not say anything about precharging.  Tried it with the cartomizer, and the battery lasted 4-1/2 hours.  Good vape & good throat hit.

After a full charge, tried the cartomizer again.  Battery lasted 8-1/2 hours.  Good vape & good throat hit.

After a full charge, tried it with the penstyle atomizer & cartridge. Very good taste, vape & throat hit.  I think I preferred this, especially when the cartridge was new.  The battery lasted about 9 hours.

After a full charge, tried it with the original atomizer & cartridge.  Not real happy with it after using the cartomizer & penstyle atty & cart.  Vape, taste, or throat hit were not nearly as good.  The battery lasted about 9 hours.

After a full charge, tried it with the drip tip.  It was awesome for awhile, but then was too much for my throat.  Tried using a lower strength juice.  The taste was not as good & the throat hit was still too much.  Battery lasted for about 9 hours again. 

That's from one of our forum members. This is pretty much "non stop smoking". This person is retired, and obviously, times on use, and taste will vary, person to person,. These actually last some folks quite a bit longer.
If you care to verify anything, I'm sure she will respond on a PM, but I'd have to check with her first, for privacy reasons.