Correct me if I'm wrong. But the max scheduled FDP is 14 hours (twice within seven days). Subtract the 90 minutes for flying five sectors brings that down to 12:30. Deduct the reporting time of one hour and the total flight time of 9:30 and you have two hours for turnarounds. Which means 30 minutes per turnaround which can work out depending on passenger and aircraft type. Not a cushy day at work, but manageable.
In my company we have a minimum turnaround table which defines normal and minimum turnarounds depending on aircraft type and type of turnaround (domestic/domestic, international/international and so on). The company council has a say whenever that gets changed. For example the lowest minimum turnaround time for a B738 is 45 minutes. Therefore we couldn't fly the schedule outlined above with that type. Even those 45 minutes will be sometimes too short if cleaning and fueling is slow, incoming and outgoing load is full and boarding is done via jetway only. For example experience shows that we can't turn around a 738 in 50 minutes on any canary island, we need at least 55, usually 60 to 65 minutes for it.