I can't understand why they seem to muck up schedules so bad, for example take a look at Newcastle to Bristol... Yeah we all want 2 daily flights at 19:10 and 20:40 don't we..
You need to think about this from the point of view of an airline manager. Presumably you would prefer to see one morning rotation and one evening rotation neatly wrapped around the business day. From a passenger perspective this makes total sense. But look a little deeper. The airline has a very limited number of aircraft available at the base in question. These are particularly high value assets. They must deploy each aircraft on whichever route will yield the highest profit for the company. If Newcastle is not that route and XYZ is, the airline is correct to prioritise the service to XYZ. Shareholders expect no less. Optimisation of ROI is paramount. Given unlimited fleet resources, the company could run all its routes in the manner you desire, but that is not the reality. You should instead applaud the airline for committing two flights per day to the NCL-BRS route, however sub-optimal you consider the schedule to be. They could undoubtedly command much higher yields by running just the one.
Just how large is the demand for day return trips between NCL and BRS anyway? Surely the vast majority of travellers would opt for a longer stay?