ok the builders are just following ill informed customer request
the link says virtually the same as what I linked - limited use to short runs, grooved helps attach anti-slip panels - lol - but the TDCA don't want to diss the customers.
and the article fails to acknowledge they were for the underside to ensure evaporation
if the maintenance burden increases and lifespan decreases with grooves up just it's form over function.
I had wrongly thought the grooves corresponded to addtional pressure treatment and was making the surface more weather/wear resistant
with no introduction on the videos I had not even bothered to disable noscript
