Hi walt178,
I would have to troubleshoot farther to understand exactly how it works. You are correct that if 3 programs are set to record according to their Guide slots and overlap by even 1 minute, one of the 3 will get bumped. But I'm not sure the same applies when the overlap is because of an extra setting. I recently had a situation similar to the OP in which I set a series to record with a 1-minute extension to prevent getting the ending chopped. Then the series played back-to-back new episodes one week. The first show recorded during its time-slot without any conflict messages, but did not attempt to record the extra minute. The second recorded without incident as well, but I can't remember if it included the extra minute I had set. The following week, it recorded with the extra minute.
So I know that the extra settings can be ignored by the DVR. The question is when and why.