I’m not sure I can help you justify more time in the pool except to say that if swimming is something that makes you happy and is good for you it deserves as much time and money as your schedule and budget permit. My pool is about 25 minutes from home but it is on my way to work so I swim in the mornings before work.

I don’t know what your current level of performance is. If you recently started swimming Masters, 3 x 1 hour per week should allow significant improvement to your swimming times. Even if you are already performing at a high level, you may be able to improve depending on your age and dedication. The key for you is to be sure the time in the pool is truly optimized to meet your goals. Make your time in workouts as meaningful as you can. Don’t swim senseless yardage with no purpose. If you are a sprinter – make sure your workouts require you to swim FAST at least once per week. 3 hours per week may be too little if you are really interested in distance events, but you can probably still improve with really smart sets. So it is important to adjust your goals to align with your ability to train (and vice versa).

You might also consider dryland work – done at home or a gym near work – to improve your swimming. Running, weights, etc. could all be a big contributor to swimming speed.

Josh Davis, the former Olympian and current Masters swimmer, said on camera during Masters' Short Course Nationals in Austin in 2008 that he trains less than 30 minutes just a few times per week. He trains HARD, using elastic bands for resistance. Josh swam 200 free in 1:36.56 at that meet, easily winning the 35-39 age group.

For what it’s worth, I train 4 times a week for about 75 minutes each workout. I continue to improve each year in my events (50s and 100s). I am faster at 50 than I was at 45.