Are you a symmetric swimmer?

I've found that much of the problems in my swimming have to do with the asymmetry of my movement (e.g. kicks in freestyle and backstroke). I've also seen Olympic swimmers or world champions were actually very asymmetric in their strokes (e.g. freestyle)--I don't remember their names. So obviously asymmetry does me bad but does some people good. So I am curious how common it is, and whether it is necessary to correct it. On one hand, symmetry is obviously preferred to asymmetry. On the other hand, what you are used to (in case of asymmetry) is better adopted than what you aren't.