One of the most common mistakes made by instructors is a lack of connection and understanding with the audience.
We can't assume the 6am clientele want the same experience as the 8:30pm. In fact, I imagine they want something quite different. It's important to be aware of the endless conditions that can affect the initial state of your audience.
Times slots, demographics, and your persona are just a few factors that may contribute to the type of people in your class. Always take a mental note of who exactly is in the room and what style of communication might work for them.
The only way to know, is to experiment and practice. Yes, intuition is valuable, but we ought to take our practice further. Try new styles of coaching and take notes after each class. Some people may want specific details, others may not. Some may thrive on an aggressive style of motivation, while others simply want to hear the music. Of course, stay true to yourself as you try new things. Authenticity is always wins, but don't be afraid to explore.
As instructors, we have the opportunity to change people's lives. Within a 45 minute fitness class, we can push people towards their greatest potential. However, the magic only happens once you've recognized who you're helping and what they need.
Know your audience. Be the change they want and need.