I am currently in Civil Air Patrol, and have been for two years. There's two types of people within CAP, those who are completely invested in the program and those who chose to attend but not invest a huge amount of their time. You're going to learn many things in either of those situations, but it is true you will learn more being more invested. I had the good fortune of joining a great squadron, but even if you don’t join the best squadron you can always search around for others. CAP offers amazing summer programs known as National Cadet Special Activities, and to attend those all you need to do is pass encampment (a week long "boot camp" for the Civil Air Patrol). These Special Activities include flight schools, leadership academies, and many more. Some of the opportunities from CAP that I've experienced are: flights in a Blackhawk helicopter, a C-130 flight, multiple glider and powered engine flights, a leadership academy, multiple bivouacs and Search and Rescue activities, and survival training. If you're interested in flying in any way, CAP is an amazing way to get your license. Also, one of the cheapest ways to learn how to fly. If your goals don't include flying, there's a huge amount of other activities within CAP that aren't related to flying (Space Command Familiarization Course, Hawk Mountain Ranger School, etc).
Here's my advice. Try it out, give it your best shot. I was worried about time management too, but if anything CAP has taught me stress and time management better than any sport or school activity I've ever done. If the program isn't suited for you, don't join. Remember that CAP is a volunteer organization, and you will never be forced to continue your membership within the program.