I would be interested to know if a standard path from Windermere to Lancaster can be found in every hour. This would actually represent a slight improvement to the service if so. It's unclear if there's platform capacity at Lancaster to turn around an 8 car every hour though.
If capacity isn't available at Lancaster to turn such a service around, its almost certainly possible at Carnforth.
I think one of the forums favourites for the North East which may raise its head is Newcastle - Morpeth / Chathill. For a couple of years its been attached to the Newcastle to Carlisles but is being detached and looks to be standalone come this December. However still not sadly possible as the reversing sidings aren't wired and currently not possible to reverse in the loops due to signalling (can't access Up loop from Down Platform, Cant access Up Platform from Down Loop and next crossover too far and will interfere with other trains quite badly)
Presuming thats Morpeth? There is an alternative place to turn back, with a signalled move though isn't there? I can't recall what it is but I was once waiting there and said unit came empty but not from the usual turnback siding.
I certainly think there are huge benefits in cutting all DMU services back to Skipton - in particular if this would be able to eliminate 75 miles/hour running and standardise an EMU semi-fast (assuming we can find the rolling stock) in 35 min every hour (rather than only in a selection of random hours and with a 2 car DMU). I would have started off with this suggestion but it's an old favourite on here along with Morpeth so I wanted to bring something new in. I'm definitely in support of developing both ideas though.
Much as they remain timetabled at 75mph, its a very long time since any diesel other than a 158 has been to Skipton, also pre Covid-19 there were a significant number of these workings, principally to Carlisle but also a few to Lancaster, that were booked 2x 158.
Yes, I would be in favour of cutting Manchester to Hull back to Leeds to Hull and stopper / fast Leeds to Huddersfield EMU absolutely. Why not? Scarborough and Middlesbrough services probably couldn't be cut into three though as that really would be taking it too far.
So Hull to Manchester can be cut into 3 but not Scarborough or Middlesbrough?! If anything I'd argue Scarborough is at the bottom of the list, and in any case, certainly in my experience commuting on this service very very few passengers board east of York and travel beyond Leeds.
Of my own thoughts:
Theres definitely something in Morpeth/Chathill. It's nothing more of a micro operation than 3x 321s as was for the Leeds-Doncaster service. I suspect that there are probably some minor works Network Rail could do to resolve the turnback issues, and of course there is already a wired depot available at Heaton. Also frees up useful DMUs for Northerns other operations.
If it wasn't for the risk of overcrowding on the remaining CrossCountry service I'd have no qualms about terminating the South Central to North East CrossCountry service at York. Perhaps if the released stock could result in HST or 2x Voyager on all of the remaining Scottish services this could work? (Of course if this option were pursed, there would be the opportunity to run a Northern all stops service Darlington-Morpeth in its place, hopefully drawing local passengers off the Intercity services through the region).
Sheffield-Adwick, I have no real knowledge of how well this service loads, but even if it is a meaningful exercise, splitting this and running an electric shuttle Doncaster-Adwick would save 2 DMUs emissions as the timetable currently means there is not only the service train, but due to being able to interwork the diagrams of the 2 stoppers to Sheffield you'd be able to save a unit from having to go ECS to Adwick and back after working the Sheffield-Doncaster service.
It's too late at night to think further afield, but I'll put my thinking cap on in the morning.