At what rate? 1% per day/week? If it takes N weeks to criss cross the Atlantic to refill from the US, maybe it is worthwhile to lose X% off the top to sell when

At what rate? 1% per day/week? If it takes N weeks to criss cross the Atlantic to refill from the US, maybe it is worthwhile to lose X% off the top to sell when possible. I have no doubt the energy companies have teams of analysts crunching the numbers on a daily basis.