I tend to think it is normal too. The Maladaptive part I think is if your daydreams interfere with reality. I have done this since childhood. I wondered sometimes if the daydreams interfered with reality but I don't think they do. They are a tool to use when nothing is going on.

I tend to do this

1. When I am on the train and there is nothing to do on the phone.
2. When I am driving.
3. Right before falling asleep.

When I was younger I had a health device that made my life not so great so this was a way to deal with it. But interestingly this was a thing with me before that.

It is my theory that the people that do this have large imaginations that require it. My entire life I have had creativity and large imagination and that can be used in appropriate ways, such as work, or school.

My sister, on the other hand, has always had a very linear way of looking at things and she doesn't have a large imagination. She was very good at school and was never very creative. She seeks stimulation from others. Very big into video games. While I never touch them. They can't compete with my head.