We have trained all of ours to come to a whistle (sports-type whistle) for extra special treats. Topper and Nicky would turn on a dime and return to me 98% of the time, and would come back after their mischief the other 2%. I used to take them to a very safe (no cars) place that was about 50 acres near a beach and a swamp, and only once did they bolt into the swamp and scare me to death, then they came bounding back, covered in muck, about 5 long minutes later.
Now we go to fenced dog parks so my training is not current, but with a little work I could probably get them to do a solid recall. I recommend to everyone I know to train their dogs to come to a whistle, the sound carries way further than the voice. I still keep a whistle hanging by the front door, in case I need it! Recall training has allowed me to take my dogs to remote beaches and let them off leash, and also hike with Topper in the mountains off leash (when he was younger).
I would never let them off leash except in a safe area (no cars!) and it is always a gamble, but with good recall training, the odds are in your favor!
Anne in Tampa, lucky to have fenced parks for the pooches