It might not be used by us and it's okay.
I use it though when I need help in figuring something out.
Instead of just using my brain I ask my subconscious to help me sort the puzzle out before going to bed and I often have a dream which I remember clearly and can't wait to apply the solution to the puzzle. It always worked.

Also some works like pendulum or dowsing involve subconscious. Some people use the name of it in their mind I was told.