Observe that for the programmer, as for the chef, the urgency of the patron may govern the scheduled completion of the task, but it cannot govern the actual completion. An omelette, promised in two minutes, may appear to be progressing nicely. But when it has not set in two minutes, the customer has two choices - wait or eat it raw. Software customers have had the same choices.
Fred Brooks...when fits of creativity run strong, more than one programmer or writer has been known to abandon the desktop for the more spacious floor.
Fred BrooksThe management question, therefore, is not whether to build a pilot system and throw it away. You will do that. Hence plan to throw one away; you will, anyhow.
Fred Brooks