piston groove

Hi all. I just read an article by weseco pistons on ring grooves. They say you don’t want more than .018 behind the ring because it takes to long for the pressure to build and push out on the ring. The last several sets of rings I have bought have a narrower top ring horizontally. So now I have over around .040+ behind the top ring. They just started doing this awhile back. Just got my short block together and read this. Why would the ring companies do this. And should I worry about it.