"High" would ruin the clothes faster and run up the utilities bill.
Personally, I run the dryer 10 minutes, then hang everything except underwear and towels. Saves a ton of cash and saves the clothes and nothing's wrinkled and in need of either more dryer time or an iron.
Oops. That didn't really answer the question though. A low setting takes longer and won't 'fry' the wrinkles into the fabric; the longer it takes to tumble and dry, the less wrinkling due to the low heat coupled with the constant tumbling. Plus, some synthetics will actually melt or at least fuse on high settings.