That's how I rationalise it in my head as well - there would be lots of information known to the crew which wasn't spelled out for the audience. Knowing which Transporter Room was active that day and which ones were undergoing the essential regular maintenance which all energy/matter scramblers require is just routine information which our heroes were privy to. And turbolifts also.To me, the workaround for the transporter is for there to be a duty transporter room and crew members were responsible for knowing or finding out which transporter room was the one in use.
That would be similar to how most Navy ships have two quarterdecks (port and starboard) but the only time when you specified port or starboard was when both were in use (like when a ship was moored to yours and that ship's crew had to cross your ship). When one was in use, it was phrases like "report to the quarterdeck" and "call the quarterdeck."
