Generally, the more you swim, the better you'll get, but how you swim is more important. You should be doing a variety of intervals, paced workouts, and drills. Extra swim mileage won't add too much wear and tear on your body (as long as your form is good). One of my athletes is only in the pool for 2500 yds, once a week, training for olympic distance races and she has no substantial swim background to speak of. Another one of my athletes is in the pool 5x a week, for about 2500-3000 yds with a masters group and he learned to swim in high school. Everyone is different and everyone has different goals. So ultimately, if you are seeing the results you want then keep doing what you are doing.
