Why Do Some Reality Checks Work?

I was wondering why when you check your watch twice, when you try to turn the light on again it doesn't work in dreams....(or at least sometimes)

I'm guessing that the lights might not work in dreams is because you take instant light for granted and don't think about how it works, why it works, should it work etc.

Some techniques don't work for certain people. Like for me, the hand RC doesn't work at all.

The Hand RC never worked for me either which is why I wasn't sure If I was dreaming or not once.