Q:

Breathing out during swimming freestyle

When breathing out during swimming, I've come across conflicting info - a swim instructor years ago told me to "exhale it all out immediately", so after I take in my breath, once my head is submerged, I breath out fully. 
I prefer, and the youtube videos I just watched support this, exhaling over time. So I'll breath in, and then once my head is submerged I'll breath out for the duration, until I turn my head to take another breath.
Is one way "better" or more efficient than the other? Is there debate between the two methods? Is one way "just wrong"?
Note linked question doesn't  deal with breathing out, this is a different question.

A:

Neither way is "just wrong", although if you breath out completely every time your face hits the water, you can start hyperventilating.
Breathing in swimming is just like any other sport, you breath in or out as much as you need to. If you are swimming at a slower pace, you may not need to breathe every single stroke, so you can exhale over a longer period of time. If you are sprinting, then you may need to breath out very rapidly so that you can inhale every stroke.
Treat it like other sports, breathe as you need to, and if you need to, learn to breathe on both sides of your stroke, it will make things easier in the long run.

