The yield of a system is theoretically unlimited (or only limited by the imagination and information of the designer).
The only limit on the number of uses of a resource, possible within a system, is in the limit of the information and the imagination of the designer.
"Our very small back yard (800 sq metres) currently produces food at the rate of 16 tonnes / hectare. I don’t know any farmers round here who get that. It also produces half of our energy needs (firewood and electricity), 500 trees and 5000 plants a year for sale, a teaching space and a soft living room." Graham Bell, writing for Permaculture Research Institute.