Similar to plumbing, it is unusual to find all the details laid out on an electrical plan for switches, outlets, 220V lines, smoke detectors, fan-light combinations, 3-ways, 4-ways, etc. Not having these takes time and causes rework. A simple way to save $100 or more per unit is planning ahead to locate electrical panels close to the service entrance.
Links:
[1] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips
[2] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-0
[3] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-1
[4] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-2
[5] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-3
[6] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-4
[7] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-5
[8] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-7
[9] http://www.housingzone.com/hz/article/top-10-waste-busting-profit-boosting-tips-8