Removing the through trains entirely except for the first and last (similar to the Sunday timetable all week) would of course help this, but we have to put up with people moaning about changing trains so we waste six car sets going all the way to Windermere and back with barely anyone on them in the evening peak from Manchester.
Changing trains would be fine if connections were of high quality and trains were punctual. Windermere does do OK on the former - cross platform northbound - but the latter, well, you've used Avanti/TPE, haven't you?
What did work fairly well in the past was the integrated Furness and Windermere timetables, whereby you had a two hourly fast (TPE) through service to each, interspersed with an all stations regional (Northern in Barrow's case, TPE for Windermere using the same unit) service in the opposite hour (continuing to Carlisle in Barrow's case, with a couple of extras added for Sellafield shifts). For Windermere, you avoided the "clash at Oxenholme" issue by running the through services fast (Kendal only), so the southbound would get to Oxenholme slightly earlier, and get out of the way of the inbound, which would leave Oxenholme slightly late and call at Kendal and Windermere only. Services at Burneside and Staveley, which are and were primarily used by locals (in so much as they're used by anyone) would operate in the opposite hour calling at all stations. This did mean less frequent services at the local stations but they're not well used.
The main downside of that was that the departure times at Kendal and Oxenholme followed a 2 hour pattern, but it wasn't that much of an issue as it was only a few minutes difference so if you wanted to remember a time you'd just remember the earlier one.
While you could question running beyond there, there is a good case for going to Preston, because you've got far more connections that can be made there without the double change.
As for sending six-cars to Barrow and Windermere, the obvious answer is to shunt three off at Preston and join them onto the southbound, reducing unit usage by one. It's like we've forgotten what benefits can be gained from multiple unit operation.
The other key reason why connections on clock face times wouldn't really work is heavy freight. The FOCs have daytime rights whether people like it or not. They're commercially valuable and won't just be given up. More loops doesn't help much for freight because it takes so long for them to climb from a standing start, so unless you're proposing to triple-track all of the hills...
The solution to the freight problem is to stop it being underpowered, and insist on everything being hauled by two high power Co-Co electric locomotives on that section. The issues are starting out and getting up Shap - a 60 or 75mph freight path an hour could otherwise nicely slot into a flighted Takt, and with enough power looping them wouldn't be a major problem. I often talk about Manchester Airport being a tail wagging a dog, but freights on the north WCML are even more so given that there's an easy and obvious solution to their eating up of paths. A single Class 66 might be cheap but is utterly unsuitable for the task.
The new down line is hardly a silly siding. It was an existing goods loop which has been modified to become a passenger line with a faster set of turnouts. Have you seen the elevation difference between the Lakes line and the Up main at the north end of the station? How are you going to fix that?
It was a "solution" on the cheap. Having passenger trains sit in a siding for 10-20 minutes is plain silly, it's just poor timetabling.
I'd have to go and look re elevation, but there are options to rejig things to allow the branch line to go straight onto the up fast.