I have not created many sketches where the images are trying to represent something in particular — I tend to lean towards the abstract. This started with wanting to create honey comb, though I was using a model of not overlapping circles by Daniel Shiffman in his YouTube series Coding Train. However, the hexagon shape did fit together as anticipated. To make this more precise would involve some more work with trigonometry.
Computer models are innately abstractions of what they are modeling. There are ways to create more realistic models, involving mathematical abstractions of phenomenon. However, I am more interested in the visual impacts of the designs and how they provoke/engage gestural interaction. Sometimes a resemblance of representation may drive a sketch, inform how it develops, though I do not strive for verisimilitude.