The reorganization of a company is a subject that has always been of particular interest to me.
This article by Elad Gil is very enlightening on this subject because it is based on his own experiences of hypergrowth within Google and Twitter.
For Gil, a company in hyper-growth will double its workforce every 6 to 12 months. The CEO will be able to handle these reorgs up to a few hundred employees. Then reorgs will no longer be global, but limited to functions - such as Sales or Engineering.
Elad provides valuable advice for founders and managers who have to go through such reorganization decisions. Highly recommended reading, even if you are not yet in a hypergrowth phase.
If your company is in hypergrowth, you will be doubling the team every 6-12 months on average. At that pace you could go from 20 to ~300 people in 2 years and to 500 or 1000 people in 4 years. You will be adding new functions rapidly (finance, HR, legal), potentially expanding internationally, while product roadmaps will expand and new areas will be launched or acquired into the company. You will effectively be working at or running a different company every 6-12 months, with most of the people at the company having joined in the last 12 months.
As the company scales and increase in complexity you will also need to change the organizational structure of the company to reflect new executives, new functions, more employees, and changing alignment against your market and product. In other words, re-orgs will occur at the company frequently.