
There just isn't enough capacity in the trains beyond 700.
probably need to use two rings, one initial ring that captures the first 5 shapes and a second ring that captures a triangle, circle square and the rest of the shapes.
If you get lucky with the station layout, I think it should be possible to string up to 7 in a single line, but if the layout is poor, then maybe 6 or 5 will be the most before the train can't keep up with demand.