I think it is important to balance that type of sketching with more “empathic” free sketching. Putting expressive lines down and seeing were they lead you. Tying different levels of emotion in the sketch.
I think the best sketches balance a constructed approach with a free approach. I actually never really did the ellipse sheets (it shows sometimes). I tend to free sketch small until I have an idea and a perspective I like. Then I blow it up on a photocopier and overlay it about 10 times to get the perspective just right, and then I overlay it like 10 more times to get the emotion and details I want. I get get it all at once, it takes me time to build on the drawing.