As everyone else has indicated, it's a tough question to answer - too many variables. But I can imagine your frustration with not getting enough "straight answers".
Here's as straight an answer I can give you based on my personal experience...
I used to smoke about 15 Marlboro Lights at day - I guess that would mean like 300 pulls on a Marb Lt a day.
I use my Vapor King a LOT more frequently than I smoked, frankly just because I can - I can take a pull on the VK just about anywhere and any time (and still be stealthy about it), where my smoking was pretty confined. I have a tough time, tho, estimating how many pulls on the VK I take a day. Here's why - I currently have 4 VK's (with diff flavored cartos) in my pocket and I flip between them all the time. I also have 2-3 full cartos in my pocket - and the 1st puff I take that taste a little "off" I pull the carto off the battery and put it in my "needs re-filled" pocket and replace it. To make it more difficult to estimate, some days are much heavier than others. When I'm in the car, I'll basically vape CONSTANTLY - take 3 pulls off 1 VK, put it down, a minute or 2 later pick up a second VK, take 3 pulls, and on and on. If I'm in the car a lot one day, I bet I use 2x the amount of juice as on a normal day.
Having said all that, since I refill all my cartos in a big batch about once a week, I can estimate that I refill about 12-15 cartos a week and get about 18 drops into each refill before it floods. So my guess is that I use about 8-10 ml of juice a week, which theoretically means the equivalent of about 1-1 1/2 brand-new cartos a day (assuming each carto gets 1ml of juice).
That's a LONG way to say, for me, I went from 15 cigs a day to about 1-1/2 cartos a day, I guess.
In terms of how many times can you refill, I've actually only thrown out 2 cartos (because they seemed "worn out") over almost 3 months of the above usage pattern. Those 2 cartos had probably been refilled 10+ times before I gave up on 'em.