The looking-at-hands technique was developed about 1,000 years ago by Sufi mystics in Iran. It was also used in the early 20th century by Gurdjieff and Ouspensky. I agree with Lucius's profound comments that "spamming" -- mindless repetition of an affirmation or activity -- is not very effective.

On the other hand, there is some evidence that subliminal messages can help lucid dreaming. There is a lot to be learned about lucid dreaming and the main thing I am getting from this Forum is an appreciation of the wide range of methods people are using. However, what we are basically doing regardless of technique is reprogramming the brain, probably the cerebellum, to generate consciousness during sleep. Developing the habit of looking at one's hands and doing a RC is a proven technique with a good reputation for effectiveness, so I encourage people to use it. Good luck.