The panels arrive in the wrong colour. Speakers are visible because no-one cut their backboxes into millwork details. The keypad station you specified at five gangs is delivered at seven. The thermostat is white plastic, mounted off-centre, in the dining room.
Nobody owns the result. The integrator points at the AV vendor; the AV vendor points at the network contractor; the network contractor points at the lighting trade. The principal looks at you.
The brief is rewritten in commissioning. Six weeks before move-in, decisions you made eighteen months earlier are reopened — by people who were not in the room when they were made — and the family is brought in to "approve" surfaces they never asked for.