For some reason, Fridays seem particularly bad for the timetable falling apart. It seems like there's too many trains scheduled in and out of the west end of Leeds for what the infrastructure can cope with. It's really common to incur 5-10 minutes delays waiting to arrive or leave, and because of how close together trains are scheduled once 2-3 are late it soon knocks on to every service
The lack of tracks, crossovers and platforms is a major part of our current difficulty when it comes to pushing more trains through the pinch points. In theory the timetables work, but only when all trains turn up at their expected times. Too many don't and one late train causes knock on effects over a wide area.
Reliable passenger services exist in the UK, like Southern to Fenchurch Street. The difference is lack of overlapping long distance services and common rolling stock.
Neither Northern nor TPE will ever be able to match the levels of reliability seen on such services. However to get nearer requires a lot of attention to minor bottlenecks that can regularly compound one little difficulty due to lack of diversionary options. Even if it's just to pull a slow stopping service into a loop to allow a faster one to pass.or maybe more bi-directional signalling at critical points.
Of course TOC management, rolling stock and personnel issues have big parts to play but we shouldn't overlook Network Rail.
Northern's PR team is up against it with all the contributory factors, and I haven't mentioned weather. With more new rolling stock bedding in it must be better by this time next year.