You're right. I cut the sessions to two per day. One 20 minute session in the morning on setting 1, and one just before bed using setting 3.
The first few days I was on it too much. It was starting to give me headaches, excessive feelings of euphoria, and even vertigo.
Since cutting back I'm still noticing positive effects, including a calm but focused mental attitude. I also continue to have vivid dreams every night, which I'm now getting used to. It's strange because I now know I'm dreaming during the dreams.