Check that they work? Sadly, all to often not true in medicine. ECT was introduced without anyone knowing why it should work, what sort of cases it works for, and so on. There was a famous case about 25 years ago in the UK, when a hospitals ECT machine had broken- but no one noticed for several months. Patients were treated in that period, and progress was apparenmtly perfectly normal...

Another treatment introduced without proper testing or a real theory was lobotomy.