Not sure what you mean by "doesn't finish at the end of each day".
TDP had an end time (besides a start time) in the territory data and the simulator would then just stop.
In CTC we decided to eliminate the end time and just let it go until the player decides to stop. I don't see what the fact that CTC doesn't finish has to do with saving the data or why it really would be needed because of this.
Nevertheless, I recognize the value to save the game and continue at another time, and I wish I had it already.