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.
Why are you concerned with a spot ? If you can not control the weight and do strict reps you are lifting to heavy , IF and only IF you need a spot it should be on your last rep or 2 of your last set . If you need somebody to spot you during your whole workout then you do not know how to train . Just being honest with ya , Hope this helps . If you only need a spot on 1 or 2 reps ON YOUR LAST SET then just ask anybody in the gym . Smith machine is nice to throw in the mix but use the dumbbells until you learn how to fully control the weight on your own then move to the barbell . Then you can switch back and forth as need be btween DB and BB once you have some experience in training the correct way . YOU DO NOT NEED A SPOTTER TRUST ME
I hate the range of motion on a smith machine. My gym doesnt have decline bench press and whenever I try that using the smith machine for it I get no chest workout from it. Imo dbells are the way to go, hammer strength, and regular bench. Also, the regular sweeping motiom of a bench press movement imo cant be replicated on the smith machine thus making it not as effective. I use the smith machine to burnt out on shoulder press, calf raises, etc.
I almost never have a spotter, my workout partner is my wife. She spots me sometimes if I really need one but obviously I have to know what im doing. Like others mentioned you should not need a spot on a regular day and still be able to go heavy during your sets.
These days I rarely use any machines. I much prefer free weights and body weight exercises. I want my body to manage and overcome the instability of the big free movements. Much more beneficial to a total synergistic body than isolating body parts.
wanna work your ego and tear pecs, blow out shoulders then do all the free benches you want...want greater pec development smith is great...so are dbs and hammer strength... beware over use injuries in old school smith machines