L.M.
My DD will be 5 in October and we STILL use the stroller for her! Her legs tire when we are walking quickly. If I am running into the store for just a few things, it is SO much easier to use the double stroller (also have a 2yo) than it is to push around one of those gigantic car carts! The two of them have more fun sitting side by side playing, and I don't have to worry about 4yo getting into things :)
ETA: I just read some other responses and I'd ask for those of you to please not assume that every 5 year old you see in a stroller is lazy. What if it's more fun in the moment for the child to be in the stroller? Less stressful for the mom? 110 degrees outside & you need to walk quickly from the car to indoors? Just finished swimming in the pool or playing at the park all morning long? Nap time? There are endless possibilities where a stroller ride for a 4 or 5 year old may be the better option. And we all know what happens when you assume. Geez.