I'm working on this modern style stand-up desk. The joinery and sculpturing are quite different than my normal 18th C. or Shaker styles. In this view, I'm not showing much of the sculpturing and shaping. And, it's worth discussing - should you spend the time in SketchUp performing this extra work.
In the case of this desk, the original piece rounds over the joints in the drawer opening. Also the stretchers are rounded and shaped to connect with the legs. My construction in the shop would be to connect square pieces as shown here, and then perform the shaping later with hand tools. I don't need the shaping in SketchUp. I need what it takes in rough lumber components to initially construct.
So the answer to how much to do in SketchUp, I would propose, depends on the purpose of the drawing. For me, the objective is producing a piece in shop, sculpturing in SketchUp is mostly a waste of time. And for me, performing this extra tedious work in SketchUp is substantial. It's much easier in the shop - With a file and spokeshave and my eyes, I can quite easily and quickly create suitable shapes.
In the following video, I will show my procedure for sculpturing the joints in the opening for the drawers. It's quite tedious with many steps. The clean-up after Intersecting was extreme. I can't go through all the steps because the video would take too long. So I'll discuss the steps involved.
Much of the process involves adding shaped components representing the rounding, and then doing an Intersection of all the graphics, with subsequent clean-up of the waste.
Here you can see the extra shapes added to the top of the tongue on the Rails, and the extra shapes added to the Side.
And here is the final assembly with the rounded joints.