Hi, I thought I should post an update.
In the end I have found that the best and fastest way to map the textures properly is with the help of SketchUV plug-in from Whaat, available at https://extensions.sketchup.com/en/content/sketchuv and that in case it gets complicated, combining the fix from Rob rspierenburg mentioned above in this same thread does wonders.
So a two-level solution for the problem, depending on the disaster grade that your geometry brings to the material 😄
Hope it helps, God knows I have been bugged by this one...
RL.