How often you drop feeders on Unitrack depends on how long you expect the track to stay in one place. If you assemble/disassemble your track regularly, then the wiping action will keep the Unijoiners conductive longer. Once you let them sit for months/years then they can start to build up oxidation that may cause voltage loss. So if you plan on not changing things for a while, you should put more feeders. Otherwise at some point you will start to have problems and then need to add feeders. If you have progressed to scenery, then it naturally gets harder to do.