1/2 AP Cost

Probably not. The upcoming Christmas lottery event has a lot of Blazes of Wisdom cuz unlike this event, you have unlimited boxes. Probably more efficient to farm those instead cuz you also get other mats as well from those boxes

If you decide to pick something up on the Thanksgiving banner and perhaps you feel you need it leveled for the xmas event, then possibly consider farming half embers. Though I don't think it's smart to use apples as the xmas 2 lottery is really good for skill gems which can be a huge pain to farm outside of an event like that so you'll want to put everything you have into those lottery boxes. And yes, all lotteries drop a good amount of gold and silver on their own so keep that in mind.

If you had a big pile of apples, it would be worth it. But since Christmas and the unlimited lottery is so close, those apples can get you just as much exp, plus material, qp, mp, fp, etc. I am going to do some qp farming with apples, but I have close to a 100 gold apples, plus some silver and bronze...

1/2 AP embers is really great. But since they're giving it to us right before a lottery that also has exp cards in it, it's not quite so attractive as it normally would be. If say that if you actively need to level your servants in order to be able to farm the lottery smoothly, then it's probably worth it. But if you've already got a good enough team to handle the Christmas quests on highest difficulty, then just save your apples for the lottery. You can still farm a decent amount of exp cards during half AP week just using your natural AP.