I think it would be retrograde, indeed, if a service such as Leeds to Blackpool were to be split into two/three individual services. (Yes, I know it's split at Preston at the moment, but, hopefully, that situation won't prevail for too long).
But a Leeds-based crew could work to Blackburn (an hour and a half's running, approximately), wait for the return train (40+ minutes), and take it back to Leeds. That would, in total, be a comfortable half a shift, I imagine.
If that looks to be inefficient, I would say that it's necessary to have a little slack in a duty, as has been proved time and again just recently. The crew continuing to Blackpool wouldn't necessarily make it more efficient.
As to Buxton crews, I don't see why they need to know Blackpool, when everyone else is trained there will be more than enough crews qualified to work the route. That is, crews from Manchester (not all rotas), Liverpool, Wigan, Blackburn, and Blackpool.