Thank for the review and tips!
The Devil is in the Details.
Great work!
Window cleaning is a very difficult task since it is made up of compound curves. Also, most of the hard water impressions on the window are only visible in the direct sunlight. I think it requires very strong chemical cleaner or microfibre cleaning cloth to clean the window perfectly. I have used ammonia once for cleaning the window but it left streaks on the glass. After that, I used to wipe the glass with a window cleaner and wipe it again with a micro-fiber cloth. Also, I used to clean the window with back and forth and then up and motion. I don't prefer circular motion. The window cleaning service providers clean in such a way. They also recommend not to clean the glass in the direct sunlight. It might leave spotty residue in the glass.