Yes and no.
It can help hugely.
On the other hand, kids spend a lot of hours in school. There should be plenty of time for them to be getting the instruction they need there. The time they are not in school should, IMO, be earmarked for other things - time outside, time with family, time for free play, time for organized activities, time for free reading, time to help with household chores. etc. I also think that having spent 6 hours in school, you are not going to get the best out of kids doing academics after school.
Especially young kids under 12 - there are so many other things they should be doing. The idea that 6 hours isn't enough time to learn to read, write and do math, as well as read lots about history, science, etc, and do activities around that, is really insane. (And FWIW, I repeated a year at age 6, and my parents scrimped that year to put me in a private school. There were half the hours, 3 rather than six, compared to my previous year. We covered all the same subjects, plus French and religion classes, and an organized class with a teacher for spots and games. It really can be done.)
A collage over the holidays is just busy work.
Even with older kids, my dd who is 17 struggles with the homework at times. She is a good student, and she is very careful about being in bed by 9:30 so she can be up at 6 to get ready for school, as she doesn't function well otherwise. She's home off the bus at 4. What she'd like to be doing is spending at least an hour, and maybe two or three, on her musical instrument most days. As well as visit a friend about once a week, keep her room clean, etc. But then she has an hour of math and an hour of chemistry and a book to read, - somehow an hour and a half a day five days a week is not enough for those subjects.
I'm personally somewhat inclined to push back against a lot of that.