Pencil strengths

[Lord Roco]

When you do pencil are, do you use a pencil with the same strength or do you vary the strength of graphite composition as you make various strokes?

I was introduced to the idea of pencil graphite strength when I was very young, but for financial reaaons, I chose to stick on with one strength. Besides, shops don't frequently sell the pencils of varying compositions and strength.

How about you guys?