Glashütte Original

"The calendar year normally counts 52 weeks, just from time to time 53 calendar weeks.

In most cases, each year starting or ending with a Thursday counts 53 calendar weeks. 

The cycle where 52 and 53 calendar weeks are displaced, repeats itself just always after 28 years.

To respect this in a mechanical watch movement, you need to construct a Perpetual Calendar

with calendar week display and a mechanism respecting this 28 year cycle, a technical challenge…

For the moment, it is not really in sight to realize something similar without any manual change at all. 

There are also other rules in other countries, where you always count 52 calendar weeks (e.g. in the US).

To enable using the calendar week display also in years and countires with 53 calendar weeks,

we decided to count until 53.  In the years with 52 clanedar weeks, it is just necessary to use the corrector one time

to jump over / skip the unnecessary 53.  For correcting it backwards, we would need a much more complex

and demanding construction."