If your goal is simply to listen for 15 minutes a day, 3 times a week, then that's great.

But if your goal is to become fluent in a short amount of time,then you will need to listen more, a lot more.

So to become fluent, and I say this because there are many different ways to define fluency,you basically need to listen to 1500 to 200 of more hours of English.

You could complete all of this listening in one year,if you spend most of your time doing it,or you could spread it out across 3, 4, even 10 years, whatever works for you.

Therefore, how much you listen really depends on you, your goals, and how you create balance.