[thackney]

When the switch was made at Pine Bend, it took about 15 seconds to decide to make 100 percent low sulfur.

That sounds bizarre. They had desulfurization capacity they were not using?

I suspect there was a couple years work prior to the switch from planing, buy and installing equipment.

[Eric in the Ozarks]

No.
Once the decision to go low sulfur, the design was made for the refinery's max production. I recall the only Midwest refinery to make both products for any length of time was Mandan.