This is what I have noticed...
If you stick the Typhoon in Turtle Mode, then take off and don't raise the landing gear and don't use object avoidance and don't record with the camera you may be able to squeeze out 20+ minutes of flight time.
If you do the opposite and fly in GPS or non-GPS mode using power to raise the landing gear, record with the camera and move the gimbal around and use power with the object avoidance here and there you'll get close to 15 minutes average. Now if you go full speed in any direction, while doing all of the above (other than turtle mode) you'll reduce your flight time down to 12 minutes.
I fly until I get the 1st low battery warning. I then flip the right hand switch on the ST16 into RTH. Once the drone is overhead I take control again for the landing.