In 1993-4 they included New Year's Day so it was a "15 day guide", however when it was repeated in the following issue there were some changes - one of which being a special second edition of Noel's House Party with the results of "Mr Blobby's Blind Date" later in the evening*, that clearly wasn't planned when the festive fortnight was taken to press.
In 1999-2000 they went up to lunchtime to cover the end of 2000 Today, and then the New Year issue was an 8 day guide to get the whole thing in one issue.
Indeed. That 1993/4 one was interesting because, as you say, some of the BBC1 programmes had changed around, so clearly it involved doing it too early for accuracy. Some of the other channels on that brief New Year's Day 2000 schedule had changed by the next issue as well. 1982/83 was also a 15 day edition, it ran Friday 24th December to Friday 7th January, which included far too much non-festive stuff. I also have the 1989 Christmas TV Times where there's half a page devoted to brief listings for Friday 22nd December, just in case that was the only one you bought.
In 1977, mind, the Radio and TV Times picked different fortnights, RT ran 24th December to 6th January, while the TVT went for 17th-30th December.
Alternatively do a 16 day edition, change the deadline dates and delay the publication date, nobody really needed to buy it last Saturday!
Given we had a 27 page thread speculating about when the BBC1 Christmas ident might be launching, bemoaning there were no "leaks" in early November, this is surely the wrong forum to be suggesting the Radio Times is coming out too early. As mentioned, it is much more complicated now because there are umpteen publications all with their own systems, many of which have presumably been created with seven day operation in mind.
Also with New Years Day being only second to Christmas it makes sense for the publishers to get another flagship issue out of it. It only happens when New Years Day falls on a weekend - based on previous years next years edition should run from the 23rd Dec -5th Jan.
Yes, the first time since 2006. In 1995, however, when Christmas was on a Monday, it actually ran from 16th-29th December. Presumably this was some kind of experiment, meaning they could do another issue for New Year (and Hogmanay in Scotland of course) but it meant week one was more or less a normal week, and they didn't do that again.
That was also the case in 1972, although in those days New Year's Day wasn't even a Bank Holiday in England.