Do professionals actually use the hanging method?
Hardly anyone does. A professional either learns AutoCAD or has an AutoCAD operator draw the plan. The course teaches every step so that you can check the work when someone else gives you a wrong drawing; anyone who can use a laptop can learn the AutoCAD needed for Vastu in a day.
Related questions
A client's location shows coordinates. What do I do with them?
Copy them and paste them into the Google Earth search bar, which takes you to the place. Then draw a straight line along a wall of the building to get the degree. A degree taken from the centre is wrong; the centre only tells you which direction a room is in.
A gallery or balcony outside a room was open at first and later covered; should it be included in the map?
Include it in both cases, covered or not. You go there and move around in it, so it counts as part of the house.
A regular plot has small strips of land left open at the side and the front. Do we leave them out or zone the complete plot?
Zone the complete plot. Almost the whole plot is in use and even the small strips are being used, so the full plot is taken for zoning and for the degree.
Can the Google Earth method be done on a phone?
Google Earth with the ruler works only on a laptop or PC. On a phone you can use a photo editing app instead: take the chakra image in PNG form, ask the client for a photo of the map and overlay the chakra on it, which needs some photo editing skill.
Can we join all the corners of an irregular plot into a square and take its diagonals as the centre?
No. When part of the plot is cut, the true centre shifts, yet the square drawn through the corners stays the same, so its diagonals give a wrong centre. Diagonals were used in the earlier zoning class only because that map was regular, with the open parking area at the side.
How can we protect ourselves when visiting a site with strong negative energy, whose effect continues even after leaving?
Protection methods are taught in later classes. Even with protection, very strong negative energy will make the body react while you are there, just as wind touches you whatever shield you make, but with a protective shield (suraksha kavach) it cannot do more than that reaction.