For now, we're just going to talk about freestyle breathing. If done correctly, the neck should hardly turn. You should breathe when your body rotates to the side. That will help to ensure that you don't throw your body position out of whack by taking a breath. Check out this short video of Bob Bowman (legendary coach of Michael Phelps and other Speedo swimmers) talk about breathing and some examples from the pros:
One thing Coach Bowman mentions is keeping your head low in the water. The drill he mentions you can do to work on this is keeping one goggle in the water and one goggle out of the water. You might think that you will inhale a lot of water with half of your mouth underwater, but when you are swimming freestyle your head creates a pocket which is conveniently located right where you are supposed to breathe. As you watch Phelps breathe in this video you can hardly even tell he is breathing because his head stays so low.
As you are swimming, make sure that you are exhaling while your face is in the water and inhaling when you take a breath. This may seem like common sense, but think about if you hold your breath underwater instead of exhaling. That means when you rotate your head to breathe you not only have to inhale, but exhale. That will take twice as long. We don't want that now, do we?
Everything I have mentioned so far is pretty straightforward and generally not up for much debate. But the question that could be debated for hours is: "How often should I breathe when I swim?" There are all kinds of answers to this question and all kinds of theories as to why each one is correct. Let's see how many times different swimmers breathe in different races:
Michael Phelps: 50m free=1 breath, 100m free=every 2 or 4 strokes
Cullen Jones: 50m free=0 breaths, 100m free=every 5 strokes
Ryan Lochte: 50m free=1 breath, 100m free=every 4 strokes
Gary Hall Jr.: 50m free=0 breaths, 100m free=every 5 or 7 strokes
As you can see there is a lot of variance between different swimmers and how often they breathe in these two sprint races. One common thing is that they hardly breathe on the super-sprints (50m). This is so that they can focus all of their energy on swimming and maintain perfect body position. The more times a swimmer breathes the more chance they have of tossing their body out of position and slowing down. Fewer breaths=fewer chance for error. It is possible for many people to only take 1 or 2 breaths in a 50m freestyle sprint because it only takes between 25 and 30 seconds or so.
For younger and more inexperienced swimmers, I strongly think bilateral breathing helps keep a balanced stroke and more efficient technique. What I mean by bilateral breathing is to breathe to both sides. That means you would probably be breathing every 3 or 5 strokes. When a swimmer breathes to just one side, they get a kind of bounce in their stroke that can sometimes lead to inefficient swimming.
Key points:
1) don't rotate your head with your neck, rotate it in line with your body
2) keep your head low and breathe out of the natural pocket you create (1 goggle in, 1 goggle out)
3) exhale underwater, inhale above water
4) hold your breath more on short sprints
5) breathe bilaterally
Remember...breathing is important! It keeps you alive, it gets oxygen to your muscles, and it can be the key to beating the person in the lane next to you.