Given the background description of some cooking related query, summarize the question into a title

Ex Input:
I've been reading "The Bread Baker's Apprentice" and all the sourdough bread recipes call for overnight storage in the fridge. Is this really necessary? Can I just leave it out at room temperature and bake it that night? What is the purpose of storing it in the fridge for a night?

Ex Output:
Cookbook says to store dough in fridge overnight, why can't I just bake it already?

Ex Input:
I recently made custard with a huge amount of milk, custard powder and sugar. After boiling it for few minutes I added vanilla essence to it. After it was settled I added apple and pineapple. Then I placed the whole mixture in the fridge and the custard was tasting fine at that time. But after a half hour of cooling, when I tasted the mixture it was bitter. I googled about the issue and found out that milk and pineapple are not good friends, but I don't want to waste the whole thing now. Is there any way to reduce the bitterness?

Ex Output:
How can I remove bitterness from custard after adding pineapple to it?

Ex Input:
I made a sauce with frozen rhubarb and raspberry mixed with sugar and reduced it until there is hardly any juice left. I put the leftovers in a sealed container in the fridge. Would this still be good? Is there anyway to tell when this is going bad?

Ex Output:
How long does a fruit and sugar mixture last?