I always give my sandbed a stir but not all of it.
You can see where you stirred last time, so you stir somewhere else.
It's a great way to feed things and dosn't hurt anything.
My water change was automated with a controller which could if need be, be activated by the press of a button.
At the moment I just do a 10% manually straight from the tank after stirring some of the bottom.
Even if the bed is deep you still need to do some vacuming but not anywhere near as often and not all of it, this helps to avoid any serious buildup.
Aaron