There are two types of reorganization, internally and externally. Internally is where your organizational chart get's a do over and Externally is where your companies are restructured to meet the current operations.
When companies starts, they start with a basic organizational chart and then grow as time goes on. The problem is if left uncheck, employees hire other employees that could be done by a single employee or, sometime, not all the times, some employees hire employees to work less. As an example, let's say you hire three carpenters, each carpenter are responsible for a job each. The problem is you hire them to take on several jobs because you though you had to many jobs on your hands, but in reality you could of hired a project manager to manage one employee that should of done all the jobs. That employee just needed help organizing his time. Now, you lost control of your organization, you need help reorganizing it's operations.
It's quite the the same for the external operations. As an example, you started several business and they have income tax loss carry forward that can't be utilized but some company would need of the tax relief, but you don't know how to reorganize your companies to utilize those taxes. It could also be that you have companies that are not profitable anymore and you don't know how to reorganize your operations to maximize efficiency.
No matter what is the issue internally or externally, sometime you just need to reorganize your operations to maximize performance and efficiency.