what to do during the holidays?

[FlorianK]

Do as much as you want it doesn't affect your score too much, there are enough students who did only chapter 1 or even less and got 45+ and there are students who finished the whole course over the holidays and got less than 40.

[BubbleWrapMan]

^This, though it's likely you will do better if you do more work, even if you don't do better than the next guy who does less work. I find it's more about besting yourself anyway...