Wind currents are everything when it comes to a dog rigging. Pay attention to your dog & which way he is facing.
With the hounds I have a couple who will rig tracks & I can tell from her strike if they are hot or cold. Now if every dog blows up, they are catching body scent & normally the hog will be within 400 yards.
Just like Jon said, a lot of times dogs can smell hogs from the top of the rig but once they are on the ground they cannot smell it. Experience will teach them & also teach you to read your dogs.
I have had dogs strike hard & go almost 600 yards to the hog itself & bay it in it's bed.
A good rig dog sure can make it a lot easier.
When rigging dogs you have to be careful and knowledgable of the wind and terrain. It is very likely in a good wind that he could have smelled a hog 3/4 mile or aA LOT further away. If he barks and you let him down and the wind calms, he can no longer trail the wind. Makes perfect sense for him to only go a couple hundred yards. In that case, you need to drive towards the wind and get closer to what he was winding.
x2...lots of times a dog with a good winding nose can wind a hog a very long ways in the right conditions but once he hits the ground he might lose the scent and then comes back...you as the handle need to decide where the hog is located as per the wind current and then walk or drive into the wind until the dog picks it back up...
