Please refer to the API code, it has been tested and confirmed before released.
In API there are more delay because of the sensor power mode change need extra delay inside. The MCU mode change only needs 7 ms and 19 ms as indicate in datasheet. But we still consider how long the physical sensor unit is ready for stable and reliable raw data to be used with bsx algorithm.
To keep data safe and consider sensor difference, enough delay time should be added.