Although soreness isn't a great indicator of how hard you're working in the gym, it can be good for some things.
There's never an instance where full-body fatigue and soreness is a good thing, but soreness in specific muscle groups might be a good barometer to determine if you're doing an exercise correctly
Overall, just remember that the only proof that your workout was effective will come from the gains you're able to achieve.
If you crush a set of biceps curls and the next day you feel soreness in your shoulders, that's a pretty good sign you need to evaluate your form.
"Workouts get longer, or workout intensity gets harder and harder," Samuel says. "Training more intensely without any regard for anything but soreness could lead to injury
That means you might not be able to gauge progress as quickly—but in the long run, you'll be better for it.
"If you're not moving those heavy weights, then you're stealthily killing your gains because you've got to move bigger loads in order to get stronger in the long term