I think you first need to decide what the ships are for. Then you can build accordingly.
Are you planning a full scale invasion of Japan or just trying to sink ships to stop japans expansion towards australia or hawaii. Another strategy might be convoy raiding or island hopping across the pacific.
Depending on your goal you will end up with very different patterns.
In my most recent games as us i have bought almost entirely subs and destroyers and very few capital ships. The subs convoy raid while the destroyers escort my transports. I try to avoid a full scale confrontation foe as long as possible
The two games that I have finished (in one go) have lasted 13 and 15 hours respectively. I have played 4 others in an ongoing format where we would play a turn every other day. All of these games lasted over a week.