Was just wondering this myself since I'm nearly out of
juice and awaiting new vape mail. I think 30 mL lasts me about 2 weeks, so that comes out to about 4 to 5 days.
I had a lot of trouble initially finding my sweet spot as far as my set up and juice were concerned. Also I have decreased nic strength from 18/24 mg initially to 12 mg and high VG currently.
I tend to chain vape a lot and feel that I've increased my consumption as I've found something that "works" for me despite the decrease in nic strength. Started as a pack a day smoker, mostly Parliament Lights.