Dale,
I have an S gauge layout built about 35 ft long and 8 ft wide, powered with Legacy Cab1-L. I have installed the ground to the entire track system but, still have a few places where occasionally an engine will lose the signal and stall with the headlight blinking. One place where the problem occurs is on a metal bridge crossing over another track, the other place is where there are three parallel tracks. This has occurred with a single engine and with engines in a consist. I am not sure if this is the kind of situation you are looking for or not.
Ray