Well, I have been vaping steady since oct 29. I was recently bragging about my 901's lasting and not burning out. However, in the past month or so, I fried about 7 atty's. But there is probably good reason. I was playing with 6 plus volts. The atty's used at 3.7, i don't recall even one of them going out.
I was even using the atty's on one of those 6 volt batteries for big flashlights rigged up when i got in a bind for a few weeks until my chuck came in. Was no problem and was a vapin machine--but touched wires together, etc. and fried a couple that way. The others were attempting to use two 3.6's in my chuck--fried on button push brand new atty. Got HV atty's on order now.
Edit: also my long lasting and abused atty's were from one source and the most recent atty's were from another source which may be a factor. They wouldn't even vape on the 6 volt big flashlight battery setup like the other one's did.