From some tutorials I notice that for drawing a wire or ribbon cable it is good practice to start with a straght line and then next do a spline and at the junction use a tangent mate.  I saw a tutorial and learned that the Fit Spline function gets rid of the junction line between the straight line and spline so that they are not visible in a render.   But the tutorial was using a 3D sketched spline when they used the Fit Spline to create a curvy wire.

After watching the tutorial I decided to make a flat ribbon cable.  Started with a line, then did a spline - but not 3D sketch.   Then did the tangent mate.  Then went to do the Fit Spline and instead of just fixing the junction it closed the two end points to make a closed sketch.  

It appears that Fit Spline works differently on a 2D vs 3D sketched spline.  Is this true?

STeve