Lines = Scales?
I have trouble replicating angles.
If I tried to copy the series of little lines in my first picture above, it would be easier if my drawing were the same size as the original (hence the basic concept of the "sight-size" technique - it's easier to draw something the same size as you see it - as a learning technique anyway - and to check your drawing by comparison. It's much more difficult when the drawing and subject are different sizes).
It would also be easier the closer I were to draw the line to the original - I could copy my little lines above no problem by drawing them next to the original lines. I could also imagine axes of symmetry and try to replicate the line across them? Hmmm, why am I having such problems with angles? .