I have general question regarding the time mentioned in the video that the rendering of the light in the bedroom will take 20 mins for daylight and approx 30 mins for night. Is this is the real timing or the time mentioned in the Blender ? Because time which blender shows is not linear with real times in my case.
Render time varies depending on your computer's capabilities. The computer I used to record this course was slower than the one I have now and it might be faster or slower than yours. But you're right that the estimated render time that Blender shows during rendering is not 100% accurate. Actual render time can vary. But it's nice to have the estimation.