Not necessarily. I keep my dog on heel when walking by the busy street. She's allowed to chase squirrels (within the limits of the leash range) on the side streets.
Not all breeds are as easily trainable as others.
But why should 1 allow a dog to run and gain more control with a longer lead in public?
If I want to *condition* my dog, I’ll use a 16-20ft lunge line, permanent. Fabric. Not a retractable which is like a knife through butter steel cable if she wants to run right by me or wrap me up. But I will not allow “walking” a dog on anything beyond old standard 6” - unless the lunge is all I have left.