Updated: May 14, 2021
For a number of years teaching perspective I've done numerous examples of plotting cross sections and mirroring them over in perspective to demonstrate the idea that "What you think it looks like on the other side, is not what it actually looks like on the other side." This is in reference to assuming what parts of an object look like when you freehand draw whatever it is you're drawing without plotting it. The most obvious experience early on in an Artist or Designer's career will be curved objects, like a nose cone of an airplane and the front of a boat. If you're a storyboard artist you will confront this exact same problem in the form of the backrest of a chair that sits behind a desk, the pilot's seat of a mecha etc. These techniques have great value particularly in the realm of object-space orientation. Honestly, in a professional environment, no one has time to draw like this, however, these are important exercises to get you attuned to more accurate guessing. The more mileage a Designer has with these types of technical drawings under their belt, the more it flows naturally into their natural drawing styles and preferences.