My husband thinks it's over kill but I find it helps keep the colours brighter.
I do now use a colour catcher at times which means I slack a little but I still like to divide them all up.
On the other hand I'm not washing mini loads of each colour everyday I wait until I've got a good load - which doesn't take too long with reds/blues/blacks etc but yellow can take a while to build up a load.
I just wondered if it was just me?