Ah, a mechanical pencil user like myself. Though in art class I used wooden pencils when I graduated my first job I jumped into was working as a manual draftsman. I immediately used the 2mm lead holders and various leads (HB to 2H). Then I discovered mechanical pencils. In life drawing class while the other artists would fumble about sharpening their wooden drawing pencils with knives I would be working with my own 2mm lead holder. Poke the lead out of the holder and then stick it into the pointer. With a smug smile on my face I rotated my hand in a circle as the lead went whisk, whisk, whisk, so much fun.
For my personal use I liked the Pentel Sharp Kerry pencil in 0.5mm. For digital art it is interesting to note that the variety of brushes found in the My Paint menu include a mechanical pencil. It’s been incorporated into the Krita program along with several others.