In early April tweaked my back in the gym. Did what I normally do with injuries, totally ignored it, worked out every day, etc. etc. until one morning it took me 1/2 an hour to get out of bed. Used a walker that day, went to the chiro the next. Within a day I traded the walker in for a cane, two days later was walking without aid. Went to see him 4 more times over the next two weeks. Within 3 weeks was back playing ball and working out.
So yeah, I'm a big believer in them, though like you and others have pointed out, some are good, some not so much.