Long layover times at distant termini

[Silver Cobra]

There's a good example of a long layover with LNER's Edinburgh services. The 1100 service from Kings Cross arrives into Edinburgh at 1519 and then forms the 1630 service back to Kings Cross, giving it a 71-minute layover.

 

[Adsy125]

Simply because they are only fast and semi fast calling patterns at that end of the route. Between Bournemouth and Waterloo they are both “fast” services (with slight differences) and basically run half an hour apart in both directions.

True, the fast still has fewer calls after Bournemouth however, and the short turnaround for the semi fast still can cause issues.

 

[Kite159]

On a Sunday where there isn't any engineering works, some of the West of England services have a leisurely 75 minute turnaround at Waterloo

 

[30907]

There's a good example of a long layover with LNER's Edinburgh services. The 1100 service from Kings Cross arrives into Edinburgh at 1519 and then forms the 1630 service back to Kings Cross, giving it a 71-minute layover.

There are several similar, simply because of how the timetable is constructed and I suspect KGX is similar.
According to RTT, the 1112 arrival forms the 1430 departure, spending a considerable time in Prestonpans Loop in between. In this case, having a unit sat spare should give considerable flexibility in coping with disruption.

 

[Glenn1969]

The 1706 LNER arrival at Aberdeen forms the 1818 Leeds departure

 

[Wilts Wanderer]

GWR turnarounds at Pembroke Dock are what they are because these are additional summer-only services which must fit in between the all-year local trains operated by TfW. In planning terms, an arrival from Paddington requires a minimum of 30 mins at Pembroke Dock before returning; this is as much a performance buffer as anything else. A 5 hour inward journey ending on a single track 50mph branch with a single passing place has potential for delay. It protects the return working’s right time start, to minimise the delay impact back into London 5 hours later.