You're not wasting your time.
Just remember that the Smith doesn't allow for natural motion.
What I mean by that is you're having to make movements based on what the machine allows rather than your natural movements based on your ROM.
I only use the Smith when I am alone (no spotter) and am going to be lifting to failure or I use it to "test" myself when moving up in weight.
Because I most often work out alone I end up using Hammer Strength a lot more than I should and the Smith when there's really no alternative.