Question about trial runs

There are mentions of 'testing' and 'trial runs' a few times during the show. In the 2nd Black Spoon vs White Spoon challenge, Self Made chef mentioned it while cooking his dish. In the same episode Chef Jin-seon (the one who was going against Comic Book Chef) mentioned that he practiced making pumpkin tartlets before settling on his dish.

My question is, are the participants given some time to perform some trial runs before they make their final dish? To be honest, I couldn't understand the time structure of the 2nd challenge since the producers were showing us every pair in a sequence.

Since the ingredient was a surprise, I don't see how they would practice making their dish beforehand unless they were familiar with the ingredient.