But contractors almost always bellyache about how much time and money it takes them to put one together!
My CO's also had a time element. If I thought that there was even a chance the CO would impact the schedule I built in a number of days for potential delay.Ultimately the cost to prepare a CO does not pencil out against the total project cost. Changes will happen, limit the cost to cost + 15% and you may find them to be reduced. Low bid + CO's can lead to delays.