Yes, schedules are published further in advance at Christmas.
Indeed, but for the rest of the year it's ten days. As mentioned, you could argue that there's no need to keep it a secret because it was fairly obvious it was going to be on that day, as that's when it always begins, but Epic Gameshow was dropped from the schedules at the last minute because they realised they were going to have to spin out the remaining content for longer, and even the biggest shows can be subject to last minute changes - all the battles in the past over Strictly vs X Factor, The Voice vs Britain's Got Talent, Big Brother vs Survivor, when programmes were moved forward, even just a day or two, to work as a spoiler.
I'd argue at Takeaway is the lynchpin of ITV Saturday winter schedules, it is as every bit as important something being shown on Christmas Day at 7.40pm - so should be no harm even in the middle of January having an end board on the trailer saying 'back from 20th February'
But what can you do with that information in mid-January? It's clearly different in announcing something's going to be on Christmas Day, or New Year's Day, because that in itself is big news as it emphasises a programme is big news. But as to whether it's going to be one Saturday as opposed to another, who cares? As I say, you can't set it to record, you'll have forgotten it by the time it comes round, and while it's obviously different at the moment, it's not going to be something you need to know to decide if you're going to cancel any plans for that night.
And also, there has to be some surprise and mystery about television, even if it's obvious when it's going to be on. Noel used to say about the House Party that the holy grail for an entertainment show was something that had a strong format but didn't look like it had a format so the audience weren't sitting there going "this is when they do this, now they're going to do that" and it got very boring and predictable. And it is more exciting saying "Coming soon" at the end of a trailer. It's supposed to be a teaser, not a binding contract.