Watch companies love anniversaries, large or small. Convention dictates that the main ones – such as the 25th, 50th, 100th, 125th and 150th – are to be celebrated with fanfare, both within the watch industry and outside it.

Because the appeal of watchmaking is so heavily dependent on history, heritage and other priceless intangibles, watch brands take advantage of anniversaries to remind the world of how long they have been around.

The question is, what makes an anniversary worth celebrating? Sometimes, all the excitement seems driven less by merit than brands looking for a reason to shout about themselves.

There is a custom in watchmaking of marking other anniversaries in between the widely accepted 25-year ones, like a 165th anniversary, for instance. And it’s not just the anniversary of the brand’s founding that watchmakers celebrate.

The founder’s birth, the brand’s first watch, first patent and so on are all fair game. That can sometimes lead to confusing numbers.

Montblanc marked its 100th year in 2006 but, earlier this year, celebrated the 90th anniversary of its signature Meisterstuck pen – issuing anniversary watches together with pens.

This practice transcends national boundaries – even Seiko does the same. In 2011, the brand marked the 130th year of its founding, while just last year, it celebrated the centenary of the first wristwatch, also the first Japanese wristwatch.

The other extreme is Rolex. Given its importance in watchmaking, in terms of size and influence – it’s the world’s largest watch brand by sales – anniversaries at the Geneva giant should be significant.

But Rolex commemorates anniversaries once every decade or so, in a restrained manner. In some ways, anniversaries at Rolex are less celebrations than a reason to introduce something new. Last year was the 50th anniversary of its Daytona Cosmograph, one of the most important sports chronographs in horological history – some vintage Daytonas rank among the most valuable watches.

To mark the occasion, Rolex released a Daytona in platinum, the first time the brand had used the pricey alloy for its iconic chronograph. But the 50th anniversary aspect was hardly mentioned, left almost as an afterthought.

One likely reason is that Rolex models have long lifespans, so the anniversary Daytona will be in the collection for years to come. Linking it too strongly to its 50th birthday in 2013 would limit its longevity in the minds of the consumer.

The strategy of using an anniversary to usher in a new model is illustrated by two earlier Rolex anniversaries, those of the 50th year of the Submariner in 2003 and GMT-Master in 2005.

The first-ever Submariner with a green bezel was presented in 2003, ostensibly as an anniversary model, though it remained in the collection till 2010, with its green successor still part of the line-up today.

Similarly, Rolex used the 2005 anniversary of the GMT-Master to unveil its first sports watch with a ceramic bezel.

But, like Goldilocks’ porridge, anniversary festivities should be just right. Too many or too tenuous, and they risk losing their meaning, while too few or without enough fanfare is something only a giant like Rolex can afford.

But, if anything, the balance should be tilted in the favour of having fewer anniversary festivities.

Patek Philippe, the grand dame of Geneva watchmaking, recently marked its 175th year in business. Its last anniversary was its 150th in 1989.

Watch enthusiasts had to wait one generation for the next anniversary, which inevitably made the 175th anniversary’s timepieces all the more enticing. Good things, it seems, come to those who wait.