This refers to the use of land that would most likely produce the greatest net return over a given time.
For example, Vendor sells house. Closing date May 31, 1995. Seller subsequently purchases a new house. Closing date and possession of March 29, 1995. Purchaser has to arrange interim financing to close on the new purchase as they do not have funds from previous home. Funds are usually assigned from the previous home to proceeds of interim financing as collateral for the loan.