I've observed that the pucks usually burn less than halfway through. I understand that this is normal and expected behavior. But since half the puck is unused, would it be (a) possible and (b) advisable to just turn them over and reuse them? That would, of course, save half the cost of the pucks.
I wouldn't, they are designed to burn for 20 mins, Bradley states that after that time you will alter the flavour when the bisquette starts to turn to an ash state.. also you would run the risk of getting debris in your smoke generator from the burnt side, and used bisquettes would be wet as they are extinguished in the water bowl after each cycle.
You can purchase savers all the same to push the last couple out on the smoking cycle and this will save you a couple.
Hope this help ya,
Johnny.