Leo is extremely bright, learning to sit the same day we had him and could give paw and lay down within one week. Far brighter than our previous two labs. But recall was never his strong point. You could offer him all of the best treats in the world, but once he latched onto another dog he was gone.
At 9 months of age whilst my mum was walking him, he was attacked by a Doberman and now has a scar on his nose. The owner knew that he dog was dangerous as she shouted to my mum, yet it was off the lead and not muzzled. The owner ran off and I wasn't there to give chase. This still didn't change Leo and he was as gregarious and friendly as ever. Something needed to change.
I was desperate and needed to reign him in, for his own safety and our constant worry. I bought a spray collar, which you control with a small remote and it sprays out a jet of harmless citronella, which startles them more than anything. These can get bad reviews but I think that's because people don't time the stimulus correctly; with conditioning timing is crucial. There's a window where you could see him thinking about whether to run or return, for maybe 2 seconds, then he was gone. If he ignored me and didn't return immediately, he'd get a spray BEFORE he ran off. Once they're running and that dopamine surge in their brain is going full-tilt, it's too late. It has absolutely worked wonders for me in a short space of time, to the point where I no longer require a lead at all and no longer use the collar. I tried everything prior to that; the collar gave me a degree of control again. It is so much more rewarding walking him without worry now. He is still eager as ever to socialise, however he now only does so when I have allowed him to. I'll ask the owner of the other dog if they're friendly and if they can play; if they say yes I'll say "Go on then!" and he'll go bounding off to greet them. People comment on how well behaved he is now.
I would recommend it when all other methods have been exhausted, and it's far from Draconian.