It doesn't have to work. The simple fact that they care and try is already a correlate of higher conscientiousness. As in, some person always trying the latest

It doesn't have to work. The simple fact that they care and try is already a correlate of higher conscientiousness. As in, some person always trying the latest productivity hack may be more productive than a normal person even if all the hacks do nothing, simply because they're the kind of person who tries to be maximally productive. Another example is caffeine is widely used as a pre-workout supplement. In high doses, without tolerance, it actually does demonstrably improve top-level strength. But the way most people use it results in tolerance and doesn't actually help. Nonetheless, the sheer fact that they're working out all the time already results in better heart health, even if the caffeine isn't doing anything on top of that.