Too many activities

[Xantheticus]

Trying to work out a balance of after school extracurricular activities. Interested in people's thoughts on whether this is too much for an energetic not very academic 9 year old boy:

Wednesday 1 hour karate

Thursday 30 min guitar then 1 hour karate
Friday 2 hrs athletics club (summer only)
Saturday 30 mins swimming lesson

Also wanting to add 30 min drum lesson. He is happy with everything now but I'm wondering if adding in the drum lesson will be too much.

Wondering how other people spread your activities through the week. If your DC do two instruments, how do you balance practice time?

I'm wondering if it's fair if one DC does two instruments when the other only does one. (Same activities but gymnastics instead of karate and keyboard instead of guitar).

DD is 9. She does:

Monday - Brownies 1.5hrs
Tuesday - County Orchestra 1hr (she plays violin, has lessons in school time)
Wednesday - nothing
Thursday - hockey training, football training (1hr of each)
Friday - hockey match 45 mins including warm up
Saturday - football match 1hr including warm up
Sunday - Pony Club 2hrs

Mine are 9 and 11 (years 5 and 7) and do 5 things a week each, we have no problem fitting in homework, reading, chill out time, time with friends etc, but they go to bed fairly late (around 9.15) and everything is very close to home so minimal travel time. Also neither of them has to come with the other to any of their activities, all of which makes a big difference. No music either.