Answer:
Going over and hanging out at a persons house isn't limited to any specific age group. It's something you do when you're really little, sometime even as a baby, and your parents take you to play (and in doing so they're getting to hang out with their friend) and you keep doing it the rest of your life, and when you have a baby you'll do just like your parents did and take them on play dates in a never ending cycle.
Going and just hanging out at a friends and watching a movie or listening to music and just talking can sometimes be just as fun, if not more fun, then going out and doing things. Kids in high school also go hang out at their friends houses to work on homework a lot.
There really is no right or wrong answer, people do both no matter what age they are
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