Both sides now.
I am starting a thread to see if there is any correlation between problems with the symmetry in your stroke, and which hand you favour as your first stroke when you start to swim.
In the pool I have been watching other swimmers, and whether it was the left hand or the right hand they started with, it never varied from length to length. I was the same until recently, and then I started different variations on each length, to try and discern the subtle differences in feel. My observations are that I am definitely slightly lower in the water when I start stroking with my left hand first. I am wondering whether this has any relevance with breathing on my left. I do favour the right side, given a choice, and this must affect the symmetry and feel of my stroke.
I started doing continuous laps of left side only breathing, and starting on each turn with a left handed stroke, until I lost any sensation of sinking slightly on the turn, then returned to bi-lateral. The improvement in symmetry is very noticeable.
In the gym I tried to find an exercise whereby I could detect this favouring of the right, and perhaps discern a weakness in the left side of my body.
I found that by doing the 'plank' exercise, and then raising one arm and its opposite leg, that I could do the movement easily with my right arm and left leg, but had to concentrate more when doing it with my left arm and right leg. As a right handed person, I do things with my right arm without any conscious effort of thought. The catch arm moving backwards and my head turning right during swimming seems completely natural, but less so on my left,which requires more concentration and effort, which must add drag.
The balance in effort for both sides since I have been working on this has added new smoothness to my stroke, and increased power.
Are there any left handed swimmers, who lead with their left arms and who have to work on their right sided breath? it would be interesting to hear your observations. Also, from anybody who feels its relevant to their swimming experience.