At BA CityFlyer it is quite normal to do 4 sector days. For example, LCY - ZRH - LCY - BCN - LCY being one of the longer ones with around 7.5 hours of total flight time. With briefing, turnaround and debrief added on you’re looking at a 12 hour day for one crew, and that’s hoping there are no delays throughout the day! It’s amazing how quickly the time passes as you’re just so busy. It’s all good fun, and there are many 4 sector days every month.