I’ve used that technique myself in the past but wouldn’t recommend it anymore. A segmented circle is supposed to be represented by its vertices, not midpoints as would be the case here. To get a model you can measure from, or somewhat easily redraw at another resolution, you want the the vertices to be at the correct radius. To achieve this you can extrude along the full circle and then erase what you don’t need.
Another option would be for SketchUp to simply properly support curve offsets and extrusions, by differentiating sharp and smooth “corners”. A corner is considered smooth if at least one of its segments is a curve. For smooth corners the offset distance is measured along the bisector, from vertex to vertex. For sharp corners the offset is measured along the segment, and the offset distance at the vertex scales according to the cosine of half the angle (or something like that), which is the current behavior.
As of now SketchUp simply doesn’t support offsets and extrusions of curves, but treat them as a series of straight edges, with the exception of some special handling for extruding along a full circle.