I am a novice HO modeler so please bear with a naive question. I have a 20 ft oval track. Should I use more than 1 Terminal Wire Connector? If so is there a "rule of thumb" re how far apart Terminal Wire Connectors should be? Thanks in advance.
Welcome. One feeder should be fine for a simple loop like that. As you add track spurs and sidings, then you should consider additional feeders. Power distribution problems in small loops come from loose track joints and can be easily fixed by lightly squeezing the rail joiners with a pair of needlenose pliers.
Terminal wire: On my 20 foot snap track loop, I did put an extra terminal set opposite the main one. Too many joints, did get an open prior. On my 40 foot loop, I used flex tracks, 1/3rd the amount of connections. Thus far, no opens with one set of terminals.