I find it interesting that you timed it with repeaters.
I’ve been using a setup where I add iron nuggets one at a time. Each time the crucible hits 2100k another nugget is added and I activate my mold. I output to an ingot mold which requires 9 nuggets, but it’ll only pour steel because it won’t use a partial amount.
I don’t have to use repeaters or redstone delays because the temperature is the key, and the delta time between 2046k and 2100k gives time for the steel conversion.
If I added iron in whole ingots, it’d not get enough KU/t during the heating phase to convert to steel.