Mirtillo isn't allowed off leash either. Only when I'm sure there is no traffic within a radius of 10 km.. When we go to such places I ask other dogowners if their dogs listen well and if it's ok that I let Mirtillo off leash.
When Mirtillo doesn't listen.. the other dogs will and I can 'catch' him.
It occasionally happens that his leash slips through my fingers, but when I call him then, he always returns immediatly. (knowing I'm having some very yummy treats)