I'm in cross country, but also in volleyball, and i also have a job (plus my paper route). All this keeps me very busy. Usually we have cc practice once a week. However, I have a paper route i do 3x a week and i always run while doing it.
My question is, will all these physical activities help me improve any? (vball practice, cc practice, running on my paper route)
If not, what would be the best exercise that would be the most time efficient?
I don't see any problem with all the things you are doing. Keep it up. I like the fact that you run to do your paper route, and you are playing Volleyball.
I'm not sure how old you are, but running three times a week if you are in 15 or younger is very good. Also, you don't want to limit yourself to just one sport. Enjoy doing both CC and Volleyball.
If you are super serious about just improving at CC, you could add one more run a week to your schedule. Make it a longer run though. That way you can build up that endurance for your cross country races.
Here's a few more tips on video about how to improve at Cross Country running.