@Tossi, I’m not saying you’re wrong here. In fact, you raise some very valid points. However, you cannot justify the expense of doubling the entire line simply owing to a pathing issue in that the trains might get stuck at some point owing to precision placement of the loops.
The fact is, and I proved it in math, that unless you position your loops in precise distances from centre then it is entirely improbable that the pathing of the trains will ultimately result in stalemate unless the capacity of the line is such that you’ve ultimately created a situation in which it would be inevitable that trains cannot path appropriately.
Also, you make a very valid point in that signal distances should always be longer than your longest train. If you would like, I can add this instruction to my guide and credit you for your submission?