I also block my tremelos (with 2 pieces of ceramic tile), so I don't use them, but I've heard that a drop of oil at the nut and on each saddle of the bridge goes a long way toward reducing string breakage because it reduces the amount of friction caused by the string sliding on the saddle and bridge. I think SRV used to do it.

I use the block rather than tightening the springs because it increases the sustain, eliminates that "wobble" that you get when you're really picking hard, and, when you're bending one string (say, the B) and letting a different string ring (say, the E), a block prevents the open E string from going flat as the tension from the bend pulls the floating trem lower on that side.