Well, when I'm testing puff counts, the whole point is to see how long a cart lasts without topping off, and I find good penstyles like Sedansa, Janty, and Litecig's 302 get around 80 5-second puffs before refilling. I haven't done a full count of any cheaper or generic pens.

When I'm not testing, on a work night I will usually go 5 or 6 hours before needing to top off. On a night off it's harder to say since I don't pay any attention to it really.

BTW, I always carry my penstyles in a lanyard which keeps it verticle. I think that helps.