I recently discovered a way to smelt more ore than I should, as evidenced by this screen capture, where all sulfur ingots were taken out from these two furnaces, from the same batch. I should have got 120 ingots (60 each), but got 140 instead. Yesterday, I got 152.
So, yeah, unless this is a known "feature", I'm all for it!
(Note: sorry for low res image... I just installed Manjaro and Shutter, and realized that it took screen caps using JPEG compression... )