TODO: Monday Morning: T1 install will be complete. Tuesday: Test/bootup period. Wednesday: Sales start Thursday: Sales continue, TV ad goes live Friday: Champagne! Reality: Monday Morning: T1 did not get installed. Tuesday: Emergency ISDN solution (stolen from Chiropractors next door) Wednesday: Modem rack catches fire Thursday: TV ad goes Live Friday: T1 goes live. Champagne.
this is why given a choice between theory/plans/estimates/schedules or, say... reality and iterating and observing what-actually-happens ... I always prefer the latter. in software engineering, in human relationships, and in the physical world around me in general.
I have worked at several places where salespeople have sold a feature without even asking if it was POSSIBLE, much less created/deployed/tested. "We just sold [Feature X], we told them it'd be ready by [date pulled out of thin air]."