The problem with leashing the dog every time you see other dogs is that the dog may learn that to avoid the leash it has to be quicker at spotting dogs than you are. It can lead to a situation where the only thing your dog does when out for a walk is look out for dogs in the hope of seeing them before you.

If you do get out when there are no dogs around - practice the signal and run. This will give her more of a chance of responding correctly when there is a major distraction. (She will still expect you to follow her calling her name when another dog appears.)