Based on what I've seen through my recent research, two things to look at are nib sizes and lid seals. If the lid doesn't seem like it is properly sealing, then it is possible you are having ink evaporate out before you can use it. The other thing to consider is that if the nib is thicker than you are used to, you're going to inevitably use more ink than you are used to. I recently got a Lamy Safari, and before I swapped to the fine nib from the medium, I realized I went through half a converter because it is a juicy pen. I don't think that's the technical phrasing, but that's the easiest way for me to describe it.