Personally, in dreams I've only ever done RCs out of curiosity once lucid ("so what DO my dream hands look like?"), or as aids to stability once lucid ("this seems so realistic, am I really dreaming?"). For me once I even entertain the notion that I'm dreaming, I get lucid. But I still do them (nose pinch, hand check) regularly in waking life, so that they become reflexes to any dream-like situation, in addition to seriously considering my environment/state. The nose-pinch helped me keep lucidity at least once when having a very realistic LD, so it's good to do them regularly!