About 1 gram per week of regular to moderate use.
If you are vaping every 2-3 hours you should expect a gram of oil to last 2-3 days of 12-16 hour days…if you’re using a vape pen or a THC vape pen
The bottom line, vape oil pens do not get my friends nor I as high as flower does. I haven’t turned my back on vape oil yet, but I am in no hurry to buy a refill cartridge – I’ll stick to my flower for now.
So for now that’s about how long a THC oil cartridge will last.