Oh, My.. This one should be good for several hundred posts!!
IMHO, taking a refresher course documents to SASS that you SHOULD know the rules and are a qualified CRO/TO. Not all CRO/TO’s are created, some good, some bad, most in the middle, regardless of recent attendance to a RO Class. If you are the type that can READ the manual and keep up with the clarifications/changes, and have good mentors, you really don’t need to take a refresher course other than for documentation reasons. Attendance is a good idea, and a good way to review and discuss recent changes, but if you don’t it doesn’t immediately disqualify you from being a CRO/TO especially at the monthly shoot level.
When making any call that isn't a run of the mill ruling, always keep, and consult a copy of the miss flowchart and pocket RO card found in the manual even when you "Think" you know the call..
F.S.