I imagine the decision is easier in somewhere like Newton Abbot southbound as people on that service are unlikely to be requiring a further connection so minimal knock-on effects.
@dk1 I wish the hourly ex-Great Yarmouth trains ran a few minutes earlier than **17, as six minutes connection onto the (usually already pretty full) Liverpool EMR at Norwich is quite stressful. The timing is just about adequate but getting a seat is another matter.
Also I wish they changed the external carriage destination display at Norwich sooner than half a minute before departure. Speaking as one who stupidly sat on a Lowestoft train thinking it was the Sheringham one, finally asking another passenger, to be put right just as the Sheringham pulled out. My own fault, confusing platforms 5 and 6, but having sat on the train on P6 for 20 minutes, looking at the train on P5 which still showed "Norwich" on the side, there wasn't much of a clue! I did Tweet them about this but I don't think it has been taken up.
Sorry, I digress.