If it's likely my deck will get shuffled no. Example: It's turn 2 and I play Impulse to find a third land, I take a fetchland, so I don't write the cards.
Anyway, when I impulse I try to remember only the important cards I'm putting on the bottom of the deck (High Tide, Reset, Cunning Wish, Flash of insight, Meditate). When I'm doing a huge Flash of Insight then I'm memorizing/writing the cards, even if it's only for half of the deck or 10-15 cards.