Why do some Supervisor training programmes fail?
First off, let me say that I believe that just about any training programme has some benefit in the overall development of people. If one attends training courses over a period of time, changes in knowledge, skills and attitude happen. But this can be a slow process, and it's expensive.
To improve results, supervisor training programmes should be based on a clear understanding of what needs to change. In addition, the material must be presented using well established learning principles. Thirdly (not to mention fourthly fifthly and sixthly) there should be support to ensure that what has been learned is implemented. This may very well be the most important factor in ensuring that the desired change takes place.
Most trainers will have faced a group of learners who say "why don't our managers attend this course, they need to know this too." And of course the managers may very well have the knowledge and skills that have been taught. The issue is that they don't always believe it, or they don't take the time to follow through and coach their staff after the course.
There are ways around this, but they are not always used - Involve managers in the decision as to what will be trained: facilitate a shortened version of the course and add coaching skills for the managers; visible support from the very top. Also, never underestimate the power of administrative systems that support the correct way to do things.
Coming to think of it, all that I have said applies to any training, not just supervisory.