Maybe it is the affiliates in certain areas then. I would think they all should follow the same schedule, but maybe there are some remote rural areas of the country where they don’t follow the guide.
But the guide data works perfectly for me. My recordings all start and end nearly perfectly. On the few occasions where it is not exact, it is usually just off by a couple seconds. The only time it is off more than this is when live broadcasts run long, in which case the end will be cut off if padding is not added. But, with the exception of live airings, I do think that trusting the guide data is the best way to use this DVR for most users. It results in the most accurate recordings. And I think it is quite impressive that I select a recording to watch and it instantly begins playing without any commercials or credits from the previous show. Too bad this doesn’t work for some people, you are kind of missing out on the great precision that this software has. It could possibly be an inaccurate time on the server. Or maybe it is the hard disks that are on some kind of energy saving setting and taking too long to spin up? Or, possibly, the DVR didn’t see any available tuners at the beginning of the show due to live viewing or other recordings.