There is smell in the air that dissipates after about the first 30 mins, if I remember correctly what I have been told. And the older the track the less air scenting seems my dog does, but of course he is not doing IPO tracking although he is pretty accurate to the track.
I have added age just like every other change or challenge, gradually and reducing if necessary if the dog struggles. Mine has done 5 hr tracks and i think thats the oldest he has done. TDX is 3-5 hrs so i have veen trying to prep him for as old as it might be.
Due to heat I have been strongly considering laying a track late in the evening and running it first thing in the morning so he can get a good aged track when it is still cool enough to work. I have not done it yet.
We have been focusing on cross tracks and getting the age right so he learns to disti guish what it will be for the test. His first cross track threw him because my track was too old too soon to go along with the cross track and so i backed it up where mine was 3 hrs and he has done great, so I will now incrementally increase my track back to 5.
I've heard after 3 it isn't that different to the dog.
Mine seemed to do better on older tracks with taller cover, I think the taller grass maybe traps more scent. So I take into account the weather, the height of the grass or other cover, and how that effects difficulty, when I decide how long to age that day so it is in line with wgatbi think he will be successful with