The timetable lists a 9 minute turnaround.
The changeover of vehicles allows time for loading (sometimes complicated by congestion with several arrivals/departures occurring together - particularly with the Arriva 685 and other GNE and Tyne Valley services).
Of course the 'delayed' vehicle then becomes the spare.
A 'delayed' driver would have a nominal 30 minutes or 60 minutes (less the delay) for an ongoing drive.
I presume they schedule a regular driver change-over at Hexham as the round-trip to Newcastle and back takes 2 hours 51 minutes (though I have seen changeovers at Blaydon)
Hexham to Blaydon takes a nominal hour.