That's why I have Variety of pencils.
4H, F, HB, 4B, 7B
4H for detailed lines,
F for Light sketches,
HB for sketching shades,
4B for darkening lines and shades,
7B for darkening darker lines and darker shades.
There are (lightest)9H~H ,F,HB, B~9B (Darkest)