We have 5 boys. None have a used a stroller past 18-20 months. All great walkers. We do our local Six Flags and have for the past 2yrs stroller free.
However, in Disney we rented a double for our then 3.5yr old and 6yr old. It was just easy. It was end of August, it was hot. Their little legs just don't move that fast. Their faces are in peoples butts. And the rain, it made it easy to pop them in it, get through the rain from the hurricane. Their feet stayed relatively dry, which was nice.
We rented in the parks, and handed it over to a family walking in that otherwise would not rent one or was in line to rent one. Paying it forward. The thank you's we got were priceless.
It was nice to have all 5 kids easily accounted for. Older 3 right near the stroller, younger 2 in it.
I did Universal Studios this past summer kids were 4 and almost 7. I did not rent, it was just me in the 5 boys. They did fine, as I knew they would. We also did San Diego Zoo and Sea World in CA, boys were then 4.5yrs and 7. Again no stroller. So next year when we go, we may skip it. Not sure yet.
So do what works for you.