Food writers are well aware of holidays long before they actually happen. I started receiving e-mails about the Mid-Autumn Festival in July and was sent my first mooncake (couriered to our office in Tai Po) earlier this month, even though the holiday doesn't take place this year until September 19. No sooner will that holiday pass than I'll start getting e-mails about Christmas; they will vie for attention with press releases about New Year's Eve celebrations and the Lunar New Year, which comes early next year (it starts on January 31).
PR people for hotels and restaurants have a difficult job: they're competing against each other to persuade journalists to give them precious column inches about their product. They try to stand out from the competition, often by sending their information out ridiculously early. Unfortunately, it's not a foot race, and being the first to e-mail doesn't mean they "win" any publicity. Others try to stick out from the crowd by using lots of superlatives about their client, hoping that at least one of them will stick (subliminally, perhaps?) in the mind of a journalist.
I can't speak for all food and wine editors, but I know what I do and don't like. The press release needs to be clear, correct and informative. You'd be surprised at how often a PR person forgets to include basic information about something they're trying to promote. I've received press releases that give incorrect dates for events; don't tell me about the price; or don't include the address or phone number of an establishment. None of this will prevent me from writing about something if it's really interesting, but if work is involved in trying to fill in the blanks, it doesn't endear the PR to me.
There's no way for anyone to guarantee coverage of any event, even if it really is as unique and fascinating as the press release claims. Yes, something new and exciting has a greater chance of being written about than, say, a restaurant's anniversary (all restaurants have anniversaries - every year, in fact). But there may be mitigating factors as to why I don't write about a particular event - lack of space on my pages, for instance; the press release coming too late to meet a deadline; or the simple fact that I'm on holiday when the information comes.
One thing I'm grateful for is that I'm now receiving almost all press releases by e-mail, rather than post. It means that if I don't want the information I can deposit it in a virtual rubbish bin rather than having to waste paper. I'm sure we've saved at least a few trees this way.