The more you think you know what you need to know, the greater is the probability that you are in need of still more learning. Learning does not come from only reading, though that is an important source.It comes from experience, interactions with other practitioners, networking with experts, among others. 

As the cliche goes, learning is a lifelong journey. While this is definitely true, it is more practical to associate the need for new learning with own career progression.

At the entry level, the most important determinant is the quality of domain knowledge the candidate has acquired during his academic life. But the job profile goes on changing and with each change, the skill set requirements also get altered. Further due to fast change in technology as well as the business environment, the half-life of the acquired knowledge gets diminished drastically. 

To be adequately equipped everyone needs new acquisition of knowledge and skills sets. This is a partial view of the demand side. This is partly because one may be looking for a career switch, whatever may be the reason. And that immediately will necessitate new knowledge and skills. 
Since we are basically talking of professionals at mid-career, the easiest and least costly option is to go for customised short-term executive development programmes. 

Many world-class universities and B-schools offer many such courses. 
But it is necessary to carry out some research to identify which institution and programme offer the ideal combination. 

I shall try to indicate the factors you need to consider in bullet points :

What are my training needs?
What outcomes do I expect?
What is the brand value of the institution? 
Will the programme attract the kind of participants I would like to network? 
Is the time -cost -value equation acceptable?

Mid-career training is expensive. Take a considered decision.