Does smelter coal usage bother anyone else?

It bothers me that the smelter uses coal based on the amount of time it's running, not on the amount of ore it processes. Like, 20 coal + 10 ore should equal 10 bars, but it doesn't because the amount of coal used is 1 coal every ~15 seconds and it takes ~31 seconds to produce a bar.

I should be able to load up the ore and coal, walk away, and come back to 10 bars, with both the ore and coal hoppers being empty. Instead, I always end up with 1 or 2 left over in either after the other has run out. It's frustrating.

I get that it's more realistic that the smelter uses fuel at a certain rate, but it doesn't make sense to say that, because the smelter isn't running constantly and using coal the whole time; it only runs if it has both coal and ore in the hoppers. If the smelter were constantly running and using a set rate of coal, regardless of if there is ore to process, I'd get it. But since it only runs with both, it should use a set ratio of both, not based on time running.