Never walk her WITHOUT a leash,never.
It's not about her,she's dog,she got instincts,maybe she wont touch humans but she'll run for cat or cars or bird or...you never know that.
I use to walk my dog without it for some time,when i realized what i was doing i stopped.
If she run you can't catch her cause she's much faster and then what?
Go without leash only when isolated in nature and that only when you're certain that she listens your commands every time.
Hope i helped.