Originally Posted by
scifi
If the direct flight takes about 20 hours, you can do the same schedule the very next day, but if the double flight takes over 24 hours.
Regardless of the route, it's highly unlikely that a stop is going to add 4 hours to the overall journey time. Bear in mind also that it won't be just a tech stop, you are also likely to be carrying revenue traffic to/from the intermediate point.
You're probably wishing by now that you hadn't asked.
By the way, did you read that link I gave you ?