Valtharius
Thinker
Patience...the one thing you can't buy.
Live models are a waste. I took Life Drawing at University and it was a waste of time. Learning how to draw distinct shapes and then putting it all together makes for good drawing. All objects, including the human body, are collections of shapes. The next problem is correct lighting. It takes a bit of practice but it can be learned.
Photoshop is only useful if you know how to draw.
For example, the company I work for uses a number of outside artists. A cover is sent to us as four small, black and white pencil sketches. Out of these, one is chosen. Next we get a color rough. It is usually approved as is but it is not uncommon for changes, some minor, some more complex, to be added. They are used to that. Our in-house artist was having difficulty with a pencil illustration and scanned and downloaded it to Photoshop. I had the privilege of guiding him through a difficult correction. However, it could have been done by hand. Photoshop was convenient but actually required the addition of two steps: scanning and detail correction using a drawing pad.
That's fine if you're drawing robots, or puppets. Models like that can be useful for blocking things out. But real people are more than a jointed mannequin no matter how sophisticated (as my teenage daughter who just looked over my shoulder and asked me what I was doing said, "well they ain't got tits for one thing have they?" which is true I suppose... I do wonder about that child.) People are all differently proportioned. We don't all fit classical Greek proportions and the body twists and turns, muscles and tendons and ligaments shape the whole way we look as we move. Puppets don't do that. Moving an arm moves muscles in the back, lifting a leg will make the person shift their weight unconsciously to compensate and reshape the body. This is why, after decades of development, 3D CGI models still have that Uncanny Valley thing going on. We can see the difference. We can't define it but we can see it. This is why drawing from real life IS necessary. Understanding the way real people hold themselves and move is important if you are going to make (representative) art that has any meaning.Wooden models of simplified human bodies are still sold. I have a plastic version from Japan. Even in the case of cartoon drawing, a model, or maquette, is made for artists to work from. They can rotate and tilt it to check their work.