Not sure how all companies handle manager training. The 2 I worked for as an employee did a terrible job. The people who promoted others to management positions, provided no training. And HR was MIA. So anyone who became a manager had to figure it out on their own.

That is a recipe for poor management and problems with managerial and employee performance. Imagine being led into battle by an untrained officer. What do you think the results are going to be? Same in business unless you get that rare person who has good sense and can figure things out.