Ive really never dwelled too much about the different drives or searched too hard for any facts regarding them, because I know there are so many opinions...however I have my notions. I think the problem is how people interpret different behaviours as being the result of a specific drive.
In regards to SchH I think the main drives which can be used are food, prey, fight, defense, most certainly pack drive! As far as when and how they are used in SchH depend entirely on the dog.
Maybe not every dog uses all of these drives, maybe they do! Im sure some would say there are more drives then this, and who knows who is right or wrong.
Pack drive IMO can be used in all phases and paints a true picture of teamwork!
I certainly fell suspect of not being aware of pack drive with my girl, until someone told me to get rid of the toy in obedience, and to stop rewarding so much, that she is highly attractable just for working with me. The longer I do obedience with my girl the more in drive she gets, and a simple smile or good girl will get her higher in drive. I often don't reward her with a toy until after an entire ob session, in less I'm working on something which warrants it more often.
In protection, so many times I see dogs who will bump/bite/look around during the B&H when the handler approaches. Perhaps because the handler creates some sort of conflict in training there, or lack of pack drive? I don't really know, but I know in ALL phases it's important to communicate to the dog when they are doing good. I often see people who don't praise or reassure their dogs enough, or the praise has no meaning, before you can communicate effectively with praise your dog has to understand what praise is, praise needs to be taught to be meaningful. Just as you need to teach your dog what wrong means! Black/White
For tracking I've heard people say to be quiet and let your dog work.. maybe Im wrong but I certainly tell my dog when she is doing good, or if she's not!
These are just my thoughts, with no founded proof, just what Ive gathered, and Ive not been doing this all that long, so I could be way off base.