To be completely honest, the days are no less busy teaching in the inquiry based approach, but they are a whole lot less stressful. Here's why. In traditional teaching, I always felt a lot of pressure to 'provide and guide'. I was on the hook for where and how learning was taking place. Being rigidly locked into a set of long-range plans added the pressure of timelines to the mix and the resulting feeling of 'I'm never going to get all this done' was unpleasant at best.
Once I adopted and somewhat refined an inquiry approach that works for me and my students, my whole teaching life became more manageable and remarkably less stressful. There's a nice flow and hum to classroom work that is more akin to a functioning workshop. People are happy. Work is getting done. Student presentations are a just reward for time well spent. Looking forward to going in to work every day, rather than sweating about how everything was going to 'get covered' is a refreshing and invigorating change. Easily achievable, too.
The great seminal researcher and theorist, Hans Selye, talked about 'distress' and 'eustress'. For those of you who don't recall the basics, 'distress' results from feelings of loss of control and can be quite damaging to the human organism. 'Eustress' is more life-enhancing. It's the culmination of internal forces that propels you to take on challenges and set goals. Inquiry teaching has tilted me strongly towards "eustress'. I love going to work, mostly because my days are now rational, I can meaningfully connect with all of my students, and explorations are engaging for everyone in the room.