Dream signs are not necessarily similarities across dreams. Dream signs are any signs that we are dreaming. Anything we realize is wrong during the dream is a dream sign. Dream signs are how we tell the difference between dream and reality.

The whole point of day work is to rehearse what we want to do during the dream. If you don't want to do a reality check or ask if you are dreaming in order to become lucid (you don't have to) you don't have to include this process in your day work.

During the day, you could rehearse identifying differences between dream and reality, which causes you to realize you are dreaming. This is what you plan to do when you're dreaming.