Tony, I think this Control Panel Setting in PS 22 at least, only applies to 'Fades' (dragging start/end of clips), as far as I have been able to determine Transitions and Ripples of Fades/Transitions cannot be forced to overlap the clips.

Transitions and Ripples always Maintain Sync, so much trimming is necessary to achieve good video and audio when using for example .m2ts files and to avoid repeat playing if using 'scenes'.