I seem to remember last year they went at pretty much the same time each hour, at least the ones towards Carlisle did.
Yes - empty coal trains tend to pass Hexham around
xx10,
although of course they don't run
every hour!
4S90, 4S12 and 4S08 (sometimes 4Z08) are the most reliable,
with 4S31 and 4S15 also running if needed.
In the eastbound direction, most daytime freights other than
6E62 and 6E65 are 'as required'
Unfortunately, the Seaton on Tees flask train (which heads
west in the 15:10 path) is not running at present, although
there is an outside chance that you could be luck and it
could restart next week.
If you want any further info on the likelihood of any specific train
running next week, feel free to contact me by PM...
MARK