In the SOU case, MAN was planned to be double daily on the ATR, but the demand just hasn't been there. Average loads are increasing but at a fairly slow rate. The Jetstream has been used more often than not, with some flights on the ATR. As a result it's planned as one daily flight for the rest of September.
Belfast is going double daily on the ATR from the 14th September as demand on that route is much higher and the use of an ATR is justified as they're carrying more pax than a Jetstream could hold.
I think it's been a case of having a plan and adjusting it to fit with the realities of the market right now. As SWBKCB says it's a mess everywhere.