I'm only 10 days in but haven't had an analog since I started. I had the same question and based on everything I read the answers were all over the map. I smoked just under a pack a day(sometimes a little less, sometimes a little more) for nearly 25 years. My smoking patterns were a bit odd. I chain smoked in bursts, lol. I smoked 4 or 5 in the mornings on the way to work, 3 or 4 at lunch, 4 or 5 on the way home, and 3 or 4 at night before bed. I never smoked in the house or around my family. You could call me a closet smoker although it wasn't exactly a secret.
Based on what I read, I decided to go for 24mg nicotine and that seems to be perfect for me, for now anyways. I expected my consumption to be about 2ml per day max and that's turned out to be the case. I've also discovered that I can't deal with 100% PG, I need at least 10 or preferably 20% VG. I plan to try 30%VG to see if I like that even better.
Because of my odd smoking patterns, it's pretty easy for me to correlate vape time and ml. of juice consumption with number of analog cigs. in my case. A completely filled 510 cartridge correlates to about 5 cigs., and a cartomizer to about 8, so for me 1 pack of analogs is roughly equivalent to 1ml of juice. However, now that I can stealth vape at home and work from time to time, and I'm always wanting to experiment with my small assortment of flavors, I'm probably closer to 1.5ml most days. This is partly due to the novelty factor, and I expect I will end up settling closer to 1 ml. per day.