While I would agree that the kids are busier as they get older, I still think I have bigger chunks of time for myself. They're all gone for at least 7 hours a day with school, so that's my time to work (again, I do the majority of my work out of a home office, so that's a huge perk for me), exercise, household chores, etc.
Once they're home from school, I'm running them around to activities (sports, band, scouts, social activities). But they're also so much more independent - I do barely anything for my oldest now! He gets himself up in the morning, makes his own breakfast, handles his homework on his own (honestly, I don't think I could help him with the courses he takes

) and just manages his time really well.
When they were little, I felt like I had to help with every little thing - bathing, getting dressed, brushing teeth, eating....it was just exhausting!