I do understand the distinction but some dogs are more prone to work the fringe than the area of strongest scent and those working in the fringe are more likely to loose the trail. Now how do we know they are on the fringe. I am going to have to take the word of a number of bloodhound handlers I have hid for..
I think alot of confusion comes from the difference between tracking and trailing.. Tracking is very close to actual track if not on top of it.. Trailing is recognized the dog can use whatever resources he needs to find the person, be it air or ground scent... My job as a SAR handler is to find that person and helpy dog however they find the strongest source of scent..
Through training and you mentioned RCMP (TTD, no?) you still focus on your dog working the strongest human scent and everything I understand is that unless there are conditions such as burn off in a field, rain, etc., the strongest scent is typically close to the footfall track (I gather from countless observations) and you want in early training to set up low wind early day scenarios where the track and trail are close so you know your dog is working strongest odor..
Yes it can leave the track. We had someone dinged once on a certification test because the subject crossed the powerline clearcut and the trail was worked at 2pm. Dog lost odor, handler boxed the area in the shade and correctly recovered the trail but got hit for getting too far off the track.
TTD high speed and reading a negative and casting to recover the trail is the first skill the handler (and their flankers!) really needs to master.
So many approaches that vary widely, RCMP, Kocher, Schettler, Johnson, that I know of.