Topcon Office Ideas

I would interpret the OP as wanting a selection method that is as brief and transitory as clicking various points on an imaginary polygon, whereby each point after two points, potentially completes the polygon.

Or something very similar can be done with a click and hold, and all movement of the cursor draws a polygon.

The polygon line could be solid and dashed when complete, to look consistent with the Magnet Office standard rectangle selection method and it could follow the convention of All, or Part of the entity, depending on which direction the polygon is started in. The Polygon method could be instigated with a press of the Shift key.

I have looked at the Selectby Area option you suggest, but what a lengthly process that is.

Are you wanting to use existing polygons in the project, or are you wanting to create a polygon on the fly then it is removed after the selection is made?
If the latter, have you used the Selectby, "Area" option and in the selection settings on the dialog use "by Points". This allows defining an area on the fly and after the selection is made removes the points used to define the area. It is very similar to creating a polygon on the fly.