If you are thinking of getting extra training in your career because you want to work in a more senior position, then you will almost always have to take some training in leadership and management. A more senior position in almost every company is usually correlated with not only more responsibilities, but also with being required to supervise and manage other staff. This type of leadership eventually requires very complex decisions that may even affect other people.
By that token most leadership and management senior positions in any company require a certain mindset and intrinsic ability to deal with and supervise people. This is usually why advanced career training positions at postgraduate levels are usually only open to those people who have had several years of leadership experience in their own field. The experience prepares them for the further training, and the training will prepare them to be better superiors.
Postgraduate career training basics
Most postgraduate courses in any field will require, in addition to some experience in the field, a great aptitude for independence and initiative. This is why it is always good to get into a postgraduate course only after you have had several years of experience in your field. By that time, you would have developed the self-starter attitude that is required to write a postgraduate thesis. If you are writing a Masters or a PhD thesis, then you will be required to make a significant scientific contribution to your field in an area that has not yet been explored by any other scientist. You are required to be a self-starter or an entrepreneur with the initiative to be a pioneer and advance the knowledge in that field.
What about non-academic disciplines?
There are also non-academic fields and more manual ones that require supervision and in these cases most people who want to be supervisors and go into senior positions will go for interdisciplinary studies. So for instance, they will take administration or management to complement their already existing knowledge in carpentry. This way they could become a supervisor of other carpenters and assistants as they are aspiring to own a furniture factory.
In any discipline, career training is important. Ultimately, CEOs and other executive members of any corporation are going to hire those people for management positions who have the requisite background experience of years working in the company, coupled with an extra training course of some sort that shows their dedication to lifelong learning.