Yep, Esther, that is disconcerning.  Out of habit now, I examine each content in the Material Room and make quick changes and adjustments for initial renders.  Images created for reflection maps are discarded because I heavily rely on skydomes and IDL for enhanced lighting.  I disassemble bump and displacement maps generated directly off image_maps and recreate them using 3rd party software.  A pain, for sure, but I have more control over how sharp or blurry I would like the map to be for better renders.  Then I evaluate the scene overall, and decide where I can skimp or enhance with shaders.  It takes longer, but I am satisfied the results.