Except that changes during the timetable period, especially due to engineering work, are not always incorporated.
.
I think it's a bit of a red herring to devalue the 'power' of the Bahn.de German Railway (aka hafas) web timetable search engine, especially at this (presumably early) stage in the OP's planning process.
The Bahn.de site famously includes some outlandish station destinations, and for Germany, Switzerland and a few others offers literally house number to house number itineraries)
The OP doesn't give us their location in the UK so I can't offer a bespoke example but I input Garsdale (Settle and Carlisle Line) to Vladivostok (Asian Russia not far from the shores of Japan...
the result:
distance: 12,300 km / 7,600 miles
journey time: 195 hours
6 changes: Leeds, Kings Cross/St Pancras, Brussels, Frankfurt/Main, Berlin, Moscow
types of train: Northern DMU, ECML 91 or HST, Eurostar, Thalys or ICE, EN sleeper, Trans Siberian Express
...
.