Talk:Experience and Rank/@comment-37971548-20191030202833/@comment-24930367-20191102022527

Old 5-4 was a costly map if you didn't use submarines.

Then some smart people in new server decided to not clear 5-4, locking it on final pattern because that one is the friendliest pattern for submarine fleet.

There was also 3CV 3CAV drum fleet. With Unryuu and co. to cut the cost, and max fuel gain from fuel node with drums.