The problem with a lot of these suggestions about set snack time, etc. is that these suggestions are coming from people with elementray age children.
It doesnt work teh same with highschoolers.
If a 16 year old with money and a car is hungry, they will go get food themselves adn a lot of times, not as healthy as whats in the house. Even if they dont have a car, if they are within walking distance to teh store, ro fast food palce, they will walk adn get something to eat. A 6 or 10 year old is not going to do the same thing.
I think the best suggestion is really just to make sure there are healthy adn filling snack.
When my brother was a teenager his favorite things to eat afterschool were:
leftovers
sandwiches
macaroni and cheese
pasta
grilled cheese
soup
Basically, he was having a second lunch. I dont knwo what the school schedule is like for your kids but for us it was:
school starts at 7:15AM (eat breakfast at like 6-6:15)
lunch was between 10:30 and noon (my brother and I usually had 10:30 or 11:00 lunch)
school ends at 2:30....by the time we got out o fteh parking lot and got home it was about 3:30
That would be 5 hours between lunch and when we got home. I was always hungry for a snack but my brotehr was always ready for a second lunch. and he would be hungry again for dinner around 6:30-7PM. And he is and always has been skinny as a rail adn he would eat us out of house and home.