Back in the days, I created a system for that.
The flight will leave at earliest possible time and come back. The next day, the flight will depart the next available time. and so on. Let's say the whole trip takes 26 hours. The Monday flight will depart at 10AM, Tuesday 12PM, Wednesday 2PM, Thursday 4PM, Friday 6PM, and Saturday 8PM. The Saturday flight will return on Sunday 10PM. You can choose to make another flight that returns before 10AM to maximize your aircraft.
If you do this, You'll have daily flights except Sunday. For that, You'll have a relief aircraft that does the Sunday flight.
Also, you can tie 7 aircrafts for a total of 6 routes in a full scale. Each route can have a different starting day, for example, route 1 will depart 10AM on Monday, Route 2 will depart on 10AM on Tuesday, and so on. The relief aircraft will just make up the route that is missed by the primary aircrafts.
I hopefully made this understandable.
This method is complicated, and you have to create each route individually, but you'll be able to use your aircraft almost all of the times.
I'm not sure if it's going to work with the updated route system. I used it long time ago.
If your trip takes just over 24 hours, try the L1011. It's fast and has a small turnaround time compared to big aircrafts.
The flight will leave at earliest possible time and come back. The next day, the flight will depart the next available time. and so on. Let's say the whole trip takes 26 hours. The Monday flight will depart at 10AM, Tuesday 12PM, Wednesday 2PM, Thursday 4PM, Friday 6PM, and Saturday 8PM. The Saturday flight will return on Sunday 10PM. You can choose to make another flight that returns before 10AM to maximize your aircraft.
If you do this, You'll have daily flights except Sunday. For that, You'll have a relief aircraft that does the Sunday flight.
Also, you can tie 7 aircrafts for a total of 6 routes in a full scale. Each route can have a different starting day, for example, route 1 will depart 10AM on Monday, Route 2 will depart on 10AM on Tuesday, and so on. The relief aircraft will just make up the route that is missed by the primary aircrafts.
I hopefully made this understandable.
This method is complicated, and you have to create each route individually, but you'll be able to use your aircraft almost all of the times.
I'm not sure if it's going to work with the updated route system. I used it long time ago.
If your trip takes just over 24 hours, try the L1011. It's fast and has a small turnaround time compared to big aircrafts.