Performance, Cost, and Scheduling cannot be specified independently. At least one of the three must depend on the others. With few exceptions, schedule delays will be accepted grudgingly, cost overruns will not, and for good reason. The time to completion is proportional to the ratio of the time spent to the time planned to date. The greater the ratio, the longer the time to go. - The Art of Systems Architecting, Second Edition, Mark Maier and Eberhardt Rechtin
