To anyone that thinks looking at a clock is a foolproof RC method, you are wrong. I had a dream where I thought I was going home, so my subconscious made the time 3:15PM on my watch. After a while, I figured time must have passed by and it was then 3:20PM.

Conclusion: If you expect a time, it'll appear. Therefore, the clock RC fails, because once you have seen a time you'll expect it to be there again.

Do note, checking a clock is a good method to get lucid. But, its not perfect.