Braniff lost a 707 on a training flight in 1959 doing Dutch rolls. It got so bad they lost 1, 2 and 4 - as in departed the airframe. We don't seem to have learned anything in 50+ years.
We used to play "whack-a-mole" in the 727. I taught guys not to try to beat down both wings, you'd just get out of sync and make it worse. Wait for your wing to start up and then roll and release, as fast as you just read that.