in all cases where you do 3d concepting you need references, thats the way to do it, either someone’s 2d art or real pictures of said object. If you get project to model ferrari f40, can you do that without reference? i sure can’t, what i would need to do is get as much reference pictures from said car from different angles and fill in the blanks if needed.
Not really sure why you think that modeling sheet in the courses are bad, they are made for those courses to show you what you are getting into if you ever want to get job in this industry.
Which is, either you get the concept provided for you, or you make 3d concept based from the object brief that describes what you need and if you are lucky it also has some reference pictures on it, and if not you look those ref pictures yourself and then proceed to create the object.
