This is an excerpt from "YOU ARE PAYING FOR PRACTICE, NOT PLAYING" -- JOHN KESSEL, USA VOLLEYBALL. He breaks down how many touches (which is how talent is built) your kid gets indoors...
"Let me explain this reality further – If your child is on a team of 12, when they are playing in tournaments, there is one person touching, and 23 others watching - including the opponents you are playing and their subs. Each side has parents usually too focused on the winning, and not the process, and each want their loving child to play. As we learn by doing, NOT watching (just think about how a child has watched you drive for more than 15 years, but has no clue to how to drive until they DO it), tournaments are not where you get good. Play in a tourney pool of four and not advance, as half the teams experience, and your child has been part of a 1 touch/23 watch totally gamelike learning experience for about 2.5 hours on average (3 matches lasting 50 min each). Meanwhile at practice, done even just twice a week for 2 hours for 2 weeks before the next tourney, with just playing you have 8 hours at a 1 touch/11 watch ratio. As about half of practice at this period is smaller group training you have 4 hours of 1 touch/5 or so watch (if doubles 1 touch/3 watch ratio, so lots of learning by doing) and 4 of 1/11 so that averages to 8 hours of about a 1 to 8 ratio – 3 times the learning-by-doing ratio and for almost 3 times as long. This means practice adds up to nearly a 10 fold level of learning for your child compared to competitions. Playing in tournaments is PART of why you practice, but if your child is not a starter, they are not missing out on that much learning by contacting the ball in those 2.5 hours comparatively. Want to get your child more learning beyond practice and tourneys? Have them go play or compete in doubles play, against anyone willing, on any surface of court, including against adults, and they will get better faster for the indoor game."