George to be honest with you. there are many hacks who rather than finding a fault on a service call, would move or add a resistor within the loop to "fool" the panel. the added cost. at most is a section of wire from the last device to the panel. very reasonable. I've been on many service calls to older systems where "t" tapping was an acceptable practice and that is a nightmare in itself. the entire point of having an eol is purely for supervision of the loop. if the eol is not truely at the last device then the supervision is void. In my neck of the woods Mass and especially R.I. the fire alarm codes are becoming more and more stringent. It is a requirement in the state of R.I to install all class "a" systems. including all slc , and Nac ckts. they even require the loop on the load side of any monitor module to be a 4c system 2 out and 2 return. your point about the wires being shorted is solved with a isolation module. most panels have the integral to the panel. and recomend they be installed every 25 devices. the iso module opens up between two of them if there is a short on the slc loop . for instance the loop may originate at the facp and pick up the front of a store say 15 devices, then hit an iso module. if there is a short within that section than the loop between the panel and that iso will come up missing, while the rest of the devices will remain intact. if that was a class "b" system then the entire loop would be lost, as the panel would not be able to poll the return loop. I've seen alot of different ways to install systems and as far as I can tell from installing and especially servicing the class "a" is the most ideal way and least likely to be compromised wiring method.