Board Thread:Questions and Answers/@comment-91.121.132.228-20150919072554/@comment-26874340-20150920082531

Here is how I would go about this...

Do your daily quests with subs in 2-3 to recover buckets and limit resource consumption. Completing daily quests will net you buckets.

Do the World-3 weekly quest in 3-3. This map drops Nagato.

When you recover buckets, start doing some of your daily quests in 5-4. This map drops Shoukaku.

If you have plenty of spare buckets, completing the daily World-2 quest in 2-5 is an option, but I would limit the amount of times you sortie here, as it is a major bucket sink.

6-3 isn't going anywhere.