Does it help to use a snoring mouthpiece at night if you struggle to obtain correct posture ?
Dr. Mew discourages the use of mandibular advancement devices, saying that the "MAD" acronym is apt, because they impose a reciprocal retrusive force on the maxilla as they protrude the mandible to keep the tongue out of the airway and prevent snoring/apnea during sleep. So they might be helpful to maintain a patent airway in the short term but counterproductive to that goal in the long term. It's also generally advised to use a morning occlusal guide after taking out the MAD to realign the mandible so that it doesn't disrupt the bite.