I do this drill a lot, but I'm not sure exactly how it's meant to be done. Are you supposed to strain your lips/mouth/tongue to build strength, or pronounce every syllable in order to make clearness a habit? Should you open your mouth wide or keep your lips tight? Should you do it until your mouth is exhausted, or just long enough to loosen your mouth and then spend more time on other drills? What have y'all found to be the most effective method? Thanks!