Ditto ArmedBear's response.
If you have ANY doubt about giving a vizsla enough exercise, you won't give him enough exercise. Saying vizslas like exercise is like saying f-16s are fast.
Tanner gets an hour at the dog park in the morning.
And an hour at the dog park at night.
Hunting season for pheasant is 3-5 days per week in the field.
And he's never really worn down. Our longest day hunting last fall was 6 hours. Tanner was only about a year old, and still didn't want to leave after 6 hours.
Amazing dogs.
OTOH, there is nothing better than spending time with my dog, and I'm never worried about him wanting to go somewhere with me.
My g/f tells me at times that she wishes I loved her half as much as I do my dog. I tell her I wish she were half as cool as my dog is.
(I'm *mostly* joking......)