Salem

So you just think you should get more iron for your efforts then.

Then in that case,
No.

Do you have any artifacts in your clothing? I don't use Alloying artifacts, but I have a modest Productivity bonus and I think I get a second bar every 3rd run. I use 13 ore and 12 lime, but that shouldn't matter.

In real metalworking this sort of thing is typical. You don't know the concentration of iron in your ore, for example, and our heating methods are immature. The results of this are low-yield processes consistent with the time frame of the game's setting as well as balanced in the game world. Later you'll have a bigger mine and all the ore you can chip. As well you'll find a large lime source. Running 3 or 4 smelters 2 or 3 times a day is not much of a chore compared with harvesting 50 cotton fields, for example.