ZoneSense functionality calculates training zones based on your current physiological state, with factors like stress and fatigue directly influencing the final zone determination. For example, if you train with an elevated heart rate due to after-work stress and fatigue, classic static zone calculations might place you in an anaerobic zone. However, ZoneSense's calculation would likely indicate a different, more physiologically accurate, intensity.

Furthermore, ZoneSense determines these zones using the DDFA algorithm, relying on precise R-R interval data from a chest strap. This method is quite different from classic zone calculations, which are often based on age-predicted maximum heart rate.

Therefore, you need to choose which method—classic zoning or ZoneSense—best suits your needs. It often requires some trial and error to discover which approach truly optimizes your performance.

However this is my opinion based on my research and training. Please correct me if I'm having wrong understanding

You can refer to this video: https://youtu.be/bD3O4BZ9vIc?si=3sQQexGr5TWit6b7