High tone in the lats can restricted shoulder elevation, external rotation, and trunk extension. It may also affect hip mobility if it is restricting pelvic tilting. The solution to "stretch" the lats often takes longer than it should. Stretching high tone may eventually promote mobility but the nervous system fights the inhibition because you are essentially trying to lengthen something that is already contracting.
A much easier way to decrease tone is to slack the muscle until it reduces, then move repeatedly in the new range. This only takes 30-60 seconds or so and is usually more comfortable.
One of my favorite tests and mobility drills is the wall angel/slide or as my colleague in the video called them "robberies."