User blog comment:BasakaNZ/Thoughts and musings on effective ship levelling/@comment-24307256-20131220064841

You can level up your DDs and CLs in 5-1, though I'm just going to say it out first that I don't know how resource efficient this method is but it is a pretty easy way to guarantee whoever you want to level up getting at least 1k exp per run while usually taking no damage. Even if they do take damage, they're DDs and CLs, they don't take long or much to repair.

This method only works for DDs and CLs, do not bring other ship classes for this unless you're too desperate for exp on them.

Equip whoever you want to level up with your best and strongest ASW equipment and place her as your flagship. All two/three(four if Yuubari) slots should be filled with ASW equipment. Equip the other 5 in your fleet with only one ASW equipment and as many radars as you have that they can equip. Sortie to 5-1 and hope for a compass roll to South. If you head South East by chance, consider it a failed run and refresh. You do not want South East, you want to purposely head into the maelstrom and the sub node. You're using only DDs and CLs so the fuel you lose in the maelstrom shouldn't be much.

Do not go into night battle. It's pretty much impossible to deal any damage to subs in night battle and you're just wasting ammo. Accept the A/B rank and you'll still get 1k exp on Flagship+MVP.

It's a good method to powerlevel one of your DDs or CLs while keeping your other unused ones up to level for whenever you have the want or need to use them.