Project lead time
Large companies take longer to start projects. How much longer?
A plausible guess is that project lead time would be proportional to the logarithm of the company size. If a company with n employees has a hierarchy with every manager having m subordinates, the number of management layers would be around logm(n). If every project has to be approved by every layer of management, lead time should be logarithmic in the company size. This implies huge companies only take a little longer to start projects than medium-sized companies, and that doesn't match my experience.
In my experience, lead time is proportional to something like the square root of the company size:
T = k a E
where T is lead time, k is a proportionality constant, and E is the number of employees. For example, someone told me that he moved to a company 1000 times bigger and things seem to move about 30 times slower. That would be consistent with a square root rule.
If T is measured in days and k = 0.5, the square root rule would say that a solo entrepreneur could start a project in half a day, and a company of 130,000 employees would take six months. That seems about right. Of course small companies can move slowly, and large companies can move quickly. But it's a good rule of thumb to say individuals operate on a scale of days, small-to-medium companies on the scale of weeks, and large companies on the scale of months.
The reason may be that large companies scale up well, but they don't scale down well. They can put together large deals fairly quickly, relative to the size of the deal, but not small deals.