Two rooms are pretty close to his 100 watt per channel home theater, and can be run up the wall, over the celing, and down the other wall with relatively short runs, 25 feet on one and 40 feet on the other. Another room takes 60 feet and the longest run takes 100 feet. Then he decides to wire some outdoor speakers that need 150 foot runs.
Since the speaker cable is a wire pair, the conductor length is twice the run length. In other words, the room that requires a 100 foot run has 200 feet of wire in the line...
...I think probably it would be best to understand that larger guage wire is going to be necessary, at least for the longer runs. The length of wire is enough to modify the response of the speakers by introducing a few ohms resistance, having a similar effect as raising Qes.