The Ballad of Gales is one of the most useful songs, as it allows you to quickly get across the Great Sea without needing to sail or superswim. As a result, the Ballad of Gales would only be skipped in a Low% Speedrun. In order to skip the Ballad of Gales, you must bypass the only required use of it, which is entering and exiting Mother & Child Isles without warping in order to receive the Fire and Ice Arrows.
You can enter Mother & Child early by performing a superswim into the island before it is fully loaded. Once inside, you can simply enter the cutscene trigger in order to receive the Fire and Ice Arrows. Although this strategy is very risky due to varying loading times, it is the fastest in a Low% run.
Go to Mother & Child and then stand on the edge of the island next to the large island that you are trying to enter. Wait for the water level to go down, place a bomb, and then Wind Waker Dive by being pushed by the bomb and then swim under the large island and enter the cutscene trigger.
Go to Mother & Child and start a zombie hover, aiming for the top of the large island. Once you are above the island, use a Red Ting from the Tingle Tuner to heal and then enter the cutscene trigger.
You can also use chest storage to walk up the tree on child isle, leaf to mother isle and climb up the island to enter early. If you combine chest storage with superswim speed, you can even slide up the island, making it even faster.
In order to leave Mother & Child without using the Ballad of Gales (since a save warp will not take you out of the island), you must perform a Ledge Clip in order to leave. Go to the correct ledge, place a bomb, use the Deku Leaf, grab the ledge, and then tap right at the proper time in order to clip. Now simply swim out of the island.
It is also possible to escape M&C without the use of bombs by grabbing the ledge with an angle and performing a roll clip in the same spot as the ledge clip.
You can also zombie hover out of Mother & Child Island. You don't even need to heal youself, just dying outside the mother island will make you respawn outside.