It can definitely help, it’s not my main method of training but it helps kind of make the mind muscle connection of speech, I usually stare into my eyes like I’m another human, practicing eye contact, or stare at my mouth especially when I reach a sound I know I struggle with to truly understand what the blockage actually consists of. I talk to my self alottt in general. Which has drastically improved my speech, kind of weird, but I’ve gotten thousands of hours of speech in I otherwise wouldn’t have, practice and repetition is very important if you really wanna make an effort towards minimizing your speech problems.