I think there are 2 parts to this question and they have been addressed already in the thread, but not in one post:
Passing the RT exam: You won't do this by listening to RT. The exam is (or was when I did it way back when) all about using the exactly correct phraseology and proceedures, including many proceedures and situations you'll be most unlikely to meet in a SEP. For this, study the relevant CAP pubication.
Being competent on the radio: For this, listening to RT is extrememly helpful, backed up by operatring in a busy traffic environment. It teaches you use of the radio in the practical manner (though not always technically correct) that real-world pilots use.