A friend of mine sends her canvas to a printer to get the photo printed on the canvas, then she paints over it.
I NEVER do that. All my canvases are hand drawn, then painted, then adjustments made when the first layer is dry.
I do mine the same way that you do. Sometimes I draw with pencil, charcoal or use a brush with a thin oil wash.
I use photos because most of my work is of animals, dogs, cats, cows donkeys etc. and animals just won’t sit still long enough to paint them from life. :)
But I never project the photo and trace it, I do not own a protector.
I don’t care who does, I just don’t like to see students do it and make big bucks selling their paintings to unsuspecting people.