My track "was" (presently dissassembled for major reparis to the elevated structure) two loopbacks that were supposed (never got around to it) to automatically throw the switch when exiting the loop so upon returning to it the train would go the other way, so the direction through the loopbacks would be 50/50 clockwise/counter-clockwise.
But, as built, with slip switches, no matter how I put the engine on the track it always eventually became a counter-clockwise operation in both loopbacks.
Also, due to the design of the steam up siding it was better to make it face to the right so the cars could be put on the parallel straight mainline; then, upon leaving the siding in the forward direction to the main and then backing up on the main, coupling to the train would be on straight track (a more ideal situation than coupling on the curve).
In the diagram below, the straightaway is about 50 ft and the loopbacks are about 17-ft diameter (and thus about 53-ft of track), making about 156 ft of running track. I want to "FILL" the center of the loopback nearest the house with a turntable and 3/4 Roundhouse.