ok. you are going to laugh, but i spend 20-24 hours per week practicing yoga/teaching. (I'm a postdoc so my schedule is flexible.) When I was an undergrad, I spent the same amount of time running track. I suspect other people are more well balanced though.
On that note, is it better to have something that you are totally dedicated to (say 10-15 hours a week), or to spread yourself out over 3-4 activities ? Breadth vs. depth? (Not that the answer will change anything for me)
it varies, but i spend more time on extracurriculars then on classes+studying on average.
that said, how much time you spend is gonna be a function of your own interest, energy, and free time. this is different for everyone, and a person who spends 2 hours/week is not necessarily inferior to someone who spends 30 hours/week on extracurriculars
