In my attic, I have mounted two Channel Master 4221 antennas that drive my high-definition Media Center PVR. Based on advice from people on various forums, I have always kept my antennas pointed in the same direction (I decided to mount two in an attempt to improve long-distance reception). At first, they were pointed towards Buffalo since the Toronto stations weren't fully rolled out yet. Earlier this year, I hauled myself up into the attic and pointed the antennas towards Toronto with its now almost complete coverage of broadcast television in OTA High Definition. However I've found that there are still some scenarios where I need to record from Buffalo stations, and the reliability of doing so has really suffered this TV season.
One might ask - if you have two antennas, why not point one at Buffalo and the other at Toronto? I've resisted doing so to this point because combining those signals may actually cause things to get worse. Take for example Fox Buffalo (WUTV). If I get a weak signal from Buffalo and then combine that with static from Toronto, then the sum of those two signals is an even weaker signal for WUTV. Similarly, a strong signal from CTV in Toronto combined with static from Buffalo combines to provide an overall weaker signal for that channel. That's the theory anyways.
In practice the angle difference between Toronto and Buffalo is less that 90 degrees, so what I get is a combination of an excellent signal with a good signal and I would hope the combination could pull in a "pretty good" signal from both directions. So I hauled my large frame through the tiny hole in the closet up into the attic to play around again. I brought my laptop, a USB ATSC tuner, and a copy of TSReader to check on signal quality in real-time while I adjusted the antenna directions. After about an hour of play, I stepped away from the setup with a good lock on every single station from Toronto, Buffalo, and Hamilton. On Sunday anyways, this would appear to support my theory of getting a "pretty good" signal all around. However only time will tell, as atmospheric conditions vary from season to season and even day to day, whether I've been able to realize my goal of consistent signal quality from all of the major transmission locales in my area.