When I was on GW staff, we would usually pre-set the tables for game nights to keep it fair, but the terrain placement rules back in those days were more fair.
At home, we use the current system, but before we roll everything else up, so it encourages a fair placement because you don't know where you will be on the table.
I haven't had the chance to play in a store during 6th yet, so I can't speak to what I'm going to encounter.