My conclusion to autoscheduling is that it is simply broken. If you look at 'ps xaw -O session' you will see that nearly everything will end up in the same group. Process group 'ps xaw -O pgrp' shows a little bit better distribution but still needs some fixes in at least the major desktop UIs GNOME/KDE.
As maintainer of ulatencyd https://github.com/poelzi/ulatencyd I came the conclusion that there is no way to optimize a system based on such simple rule. You need workarounds and heuristics and also contact to the X server etc.