That's the thing though, the 10% number is fuzzy. I agree there's definitely a productivity boost from having a private office, but it's hard to quantify. The smaller square footage and lower lease payments are easy to quantify. If productivity expectations are set based an open office, then the increase with the more expensive private offices is unknown.

Additionally, high overhead increases risk. Maximum productivity is only important as long as you have more work than there are employees to do it. What if there's a downturn (as in 2008)? Now you're locked into an expensive lease and no longer have the revenue to support it. The company with lower overhead can hold out longer until things turn around. Employees can be laid off. Getting out of a lease or selling a building are harder.