Actually, that's not the question to ask...where would you have them operate to and at what frequency so as to maximise the aircraft time and the revenue-earning potential while not driving up the crew costs to such a level as to make the whole thing uneconomic in order to make the utilisation "efficient" in your eyes.
I await your wisdom, O wise one
Its just my opinion. I am not going to waste time arguing my case. But if one looks at say for example FR's Dublin Base. They can achieve a greater number of flights per day from their aircraft given the mixture of their short haul routes to the UK and their longer routes to Europe etc. The combination of both many short haul and longer routes from DUB enables FR to achieve excellent aircraft utilisation. EI serve 6 UK Airports from Dublin. FR serve 14 UK Airports from Dublin. Operatings costs may increase but fixed costs remain the same.