Definitely depends on the child. Because this is anonymous I will admit that my DD1 (year 5) does an afterschool club plus another activity on Mondays, has to come to her sister's swimming lesson on Tuesdays, does an activity on Wednesdays, we always have some out of school friends round to tea on Thursdays, Music lesson on Fridays (and until recently an activity as well), and all Sunday morning doing an activity.
She never goes to bed before 9pm, more usually 9.30pm although I confess it was 10pm tonight. She bounces out of bed at 6.30am and never appears tired.
However, she has friends that go to bed at 8pm and who are horribly tired at school the next day if they stay up later than 9pm.
Yes, I do think my DD does too much after school, but she thrives on it. Costs me a fortune though