Some other cities were offered as examples. I offer Copenhagen – Central, Norreport and Osterport stations.
Copenhagen Central; is the main station and is located south east of the city centre and serves locations west, south and to Sweden.
Norreport is north of the city centre.
Osterport is north east of the city centre and when built was a terminus for the lines north to Helsingor. In 1917 a cut and cover tunnel was built from Osterport station to Central station with a new station at Norreport. The tunnel is 4 track – 2 for mainline services and 2 for S-tog service.
One mainline service is the Oresundtag service from Helsingor-Niva-Osterport-Norreport-Copenhagen Central-Copenhagen Airport-Oresund Bridge-Malmo- other Swedish destinations. The service frequency between Niva and the airport is every 10 minutes both ways from the start of the am peak through to the end of the pm peak Monday to Saturday and this 10 minute frequency dictates the complete timetable through the Central-Osterport section.
Most of the other services into Central station do not terminate at Central but continue northwards through Norreport and terminate at Osterport so the Central-Norreport section is heavily used giving rise to 3 trains every 10 minutes at peak hours which is very tight and at least 2 trains every 10 minutes for the rest of the day. A small number reverse to go to/from the airport to provide a limited number of through services to/from the airport to more distant parts of Denmark. I do not think any Danish services terminate at Central except at maybe the start or end of the day. The Swedish Railways service to Stockholm terminates at it own separate platform south of Central station.
All trains stop at Central, Norreport and Osterport for passenger convenience and operational ease (easier to manage if all trains have the same operating profile). To reverse trains at Central requires more platforms for which the space does not exist – and this is recognised as a problem which may be addressed in the future as there was a desire (pre Covid) to add 4 more platforms to cope with growth and more trains.
In practice, 3 trains every 10 minutes does not always work and so towards the end of the peak some services are typically up to 10 minutes late. There are several features of the track layout which help in mitigating delays, scheduling services and resequencing services.
South east of Central station the lines diverge – south east to the airport and west for the rest. At Central there are 4 platforms in each direction and any service can use 3 out of the 4 platforms so flexibility. As Central is the main station, there is a lot of interchanging, particularly passengers with luggage going to and from the airport so actual dwell times vary from 1.5 minutes for an emptier train with no passenger luggage to 4.0 minutes for a busier service with a lot of passenger luggage and passengers both alight and broad very train. The timetabled dwell time varies between 3.0 and 10.0 minutes to help with train sequencing on the approach lines and the Osterport line.
Heading out of Central towards Norreport, the 4 northbound tracks reduce to 2 northbound tracks and the length is such that a train can be held here and also passed, then the 2 northbound tracks reduce to 1 the northbound track through the tunnel.
Norreport station is 1 platform in each direction and this is the pinch point. This station is popular with Copenhagen residents for offices and shops so no luggage on and off.
The single northbound line continues to Osterport where there are 2 platforms in each direction. [Note southbound ahs the same number of tracks]. The outer platforms are normally to/from Helsingor and the inner platforms are for terminating/starting services with trains being able to use both platforms. The dwell time at Osterport is short as it is the least used station and terminating trains arrive almost empty so are quick to clear. North of Osterport, the Helsingor line divides some 100m+ apart and in the centre are a number of reversing sidings and one half of a train depot (the other half being accessed from a dive under).
Also, note the line speed approach throughout the whole Copenhagen area. There are no slow speed points used by passenger services whether in service or going in or out of service off the mainline. All points are of ‘line speed’ capability so drivers do not need to slow down for a change of platform or to take a diverging route. There are also plenty of points in the area to maximise flexibility of routing/platforming and with ‘line speed’ points the changing of a route does not incur a time penalty, not even of a second or so.