^^That.

RC's do not make you lucid; they confirm lucidity.

You really cannot honestly do a RC in a dream unless you already think you are dreaming (aka, have some lucidity). If you are not lucid, then you are simply dreaming that you are doing a RC, and its result will be whatever your dreaming mind offers (i.e., you could very well have a NLD about your RC failing and your DC you will assume it is lucid, even though you never really are - or, on the other hand, you might dream that the RC has proven that you are not sleeping)). Oh, and as long as I'm here: that whole "seeing something odd and then doing a RC to make you lucid" thing is also not a thing, because there is nothing odd in a NLD, ever. If you see something odd in a dream, then you are already at least slightly lucid, and doing the RC only serves to confirm and perhaps amplify that lucidity.

All that said, RC's may be the most valuable technique we have in our lucidity toolbox. This is because, as NyxCC just said, when practiced sincerely during the day, RC's do quite a bit to help you establish that lucid mindset you need to notice that you are dreaming during a dream. If you keep your RC simple, and maybe follow up each one you do with some thoughts about dreaming, you will be helping to prepare your mind to have a desire to be aware during the dream (that really needed a whole lot more words to explain).

Remember also that RC stands for Reality Check; not Dream Check. It was meant from the get-go to confirm that you are awake, and not dreaming.