While this method might be easier and less expensive, in my opinion it doesn't hurt to have a smaller, fully confined and roofed run attached to the coop. In the event that you have heavy rain or heavy snowfall, your chickens are not going to want to come out and make use of the entire fenced, un-roofed enclosure. Plus you'll have emergency backup if you discover some problem with your electrified fencing at 7:30 in the morning just before you have to leave for work. While your chickens might be OK confined to their coop for a day if weather or emergency mandates it, several days or a week will result in a variety of problems unless the coop itself is way oversized for your fllock.
