When I first learned to swim front crawl (freestyle), my swim instructors all the way to the highest level of swimming badges taught to breathing on one side. I was a one sided breather until I started competitive swimming. My coach was a Physics teacher by day and threatened to kick us off the team if we didn’t breath from both sides, either every third, fifth or seventh stroke. I was furious with this change but scared of being caught not doing otherwise. It took me some time to get used to it but I finally did it so much (having to do much more laps than I had ever done in swimming lessons) it became the way I did front crawl. I continue to swim every third stroke.
There are far more benefits to bilateral breathing than one sided. It’s faster, more symmetrical, the shoulder remain balanced.
If you’re swimming as a recreational sport, the benefit of speed won’t matter but the imbalance of shoulder muscles will. Learning bilateral breathing will teach you better controlled breathing. At first it will seem like you’re out of breath, but with practice, the stroke will glide more naturally and so will the breathing.
I’m thankful for that coach who forced me to use bilateral breathing. I think that we should learn this type of breathing from the moment we learn front crawl.