Instinctive

Slim your right to question this as it can be over complicated.

The Old Man explained it the best but I will simplify it even more. Its simply a dog lifting his head and running the scent in the air in a more direct line. It can be faster because if that hogs been weaving a little or meandering around instead of following every little weave in and out, it will just run a straight line through it making up ground on the hog. Your dogs probably do it and you just didn't know that is what people call it, as most stock bred cur dogs drift, some more than others. That is the main way winding type dogs run a track from what I have seen. Now how much a dog will drift is a different story, some get real good and start what us cat and fox hunters call cheating, in which they will "swing" and "drift" a track a lot more, sometimes more than the scent will allow. This is a double edge sword, because if the dog is really good at knowing how the game runs he will catch a lot of game a lot quicker, but if he is not this is where dogs make big losses and can end races. You can really see this cat or fox hunting big packs of dogs on the Garmin due to the way cat and foxes run. This is why a lot of these houndsmen like to have both in their pack and when the dogs have run together enough the cheaters will even learn that when they lose the track that they can go back to the voice of a certain dog they trust (track straddler) and get back on the track and try to get back in the race though sometimes they are too far behind.

Also if the hogs you are running are just running straight lines then drifting or track straddling doesn't make as much difference, whats makes the bigger difference in this case is running heads up or nose down. Just some observations I have made.