Nice curves
If you look at professionally designed components you will often see smooth curves.
Parts with smooth curves are good for DFM (design for
manufacturing) and look good.
For another example, we might want to go from:

To make smooth shapes srrounding holes and/or cutouts:
- Delete the outer shape (e.g. the large rectangle above).
- For each hole or cutout do Line | Contour | Outside.
- Select all (Ctrl+A).
- Line | Intersect.
- Delete unwanted segments.
- Where needed: select two arcs from the contours; apply Line | Tangents.
- Select all (Ctrl+A).
- Line | Intersect.
- Delete unwanted segments.
- For any two lines meeting at a sharp angle, select them and apply Line | Corner | Round.