Continuing the discussion from Download Leica total station points into sketchup pro 2015:
**… in which it was said to never set any layer, except "Layer0"as the active layer …
That is not really true. Primitives need to go on Layer0.
But sometimes it is necessary to put other things like SectionPlanes, Text Notes, etc., on other Scene specific layers. If doing a number of them, it is faster to switch to the appropriate layer, rather than set the layer piecemeal via the EntityInfo dialog. The same goes for inserting components. If you’ll be inserting many doors onto a “Door” layer, switch to that layer and insert the components.