Panderson55
I'm going to agree with your friend, but with a caveat.
By the time I let my dogs "off the chain" for the first time, There has been a ton of obedience work performed, and many, many "play sessions" in the yard with live quail. The dogs have already been running with a 50 foot checkcord attached, and a bell on their collar for a few months, so the picture is being established . Owner+Bell = Bird= Fun. So, by the time I really turn them loose, I'm fairly confident that I can get them back. They've been allowed to have their head, but under control, for months.
If you try to keep the dog too close there is a strong posibility that the dog will "shutdown" on you, and not begin to actually hunt, because it's awaiting your next command. You have to let them off the chain. I'm actually working through this issue with Tika right now. I've tried to run both dogs together but Gunnr requires a firmer hand and more voice. Tika can't seperate Gunnr's commands from those directed at her, so she just heels up and won't range out. I have to work them seperately now. Tika is a much more sensitive dog than Gunnr, and requires very little handling.
It is eerie how a Vizsla will adjust it's range, based on cover and conditions, along with time and experience. It's also eerie that with time and experience they begin to gravitate to more productive cover on their own. It's a symbiotic relationship that develops with time between you and the dog. You have to trust the dog. Mine have proven me wrong so many times through the years that I just let them lead, which is their job after all. I promise you that you will be the limiting factor. They know more about hunting than you or I, and all we're really trying to do is to get them to hunt with/for us.
If all of the "pictures" have been presented properly your dog will associate you with the hunting, and while they may blow some steam off for the first 15-20 minutes, they'll settle down. Swing them through non productive cover for the first 20 minutes and them bring them into the cover you really want to hunt. As they get older and acquire more experience they won't require this little "warm up". They'll move right off from the vehicle and start hunting.
Everyone is afraid of their dog running off, but to hunt effectively they have to be given free rein.
It's a lot easier to bring a dog in, than get one to move off.