I studied at Kelley School of Business in the US.
It’s fashionable now to trash the MBA about as much as consulting, but it’s actually a great school too. The main thing it gives you is a leveling of knowledge and skills.
If you grew up as an engineer, a salesperson or a marketer, there are almost certainly areas you don’t know. You can’t build financial models, you don’t really understand accounting, you don’t know operations, marketing or corporate finance. After a good business school you at least have a proper map of the whole system.
And practical experience then settles onto that theoretical knowledge very quickly. And it’s not entirely theoretical — all good schools use the case method, and over two years you go through hundreds of cases from different industries.