The vast majority of shade sails are made by joining flat fabric strips together and then marking the shade sail shape out on top of the large panel and then cutting it out.
The result is a flat shape which when installed, is forced into a 3D shape through shearing force. While this approach appears to work, it is often only short term, ultimately there are limitations and typically these sails will have a shorter life than a properly patterned sail. These sails will often be flatter than desirable in order to overcome wrinkles in the body of the sail which result from lack of proper patterning.
While you may be shown photos of apparently excellent sails as evidence to demonstrate qualifications and competency, bear in mind it is unlikely you will be shown photos of the large number that “didn’t quite work out” or photos of the “nice sails” a few years later when they have either sagged or flogged themselves to destruction like those shown above.
Correct patterning results in a 3D shape when the fabric panels are joined without the need for shearing force. The strips of fabric have curves cut in the sides which are defined by 3D patterning software and are usually cut on a computer controlled plotter/cutter