It really depends on whether the activities are in balance with the rest of the family's commitments.

My DD1 at the same age only did one activity per week (sport on Saturdays) - this was enough for our family since we were both working full-time and she was in afterschool care all week. However, the care provided a number of different activities and so I figured she was getting plenty of variety, if that makes sense.

When she was a bit older, she joined Scouts and then Guides. Guides was a winner and has been a constant since. She has also done a variety of sporting activities since then as well. So for us, the balance has been for the kids to do one sporting and one other activity - with one of those usually being on the weekend.